Does a downpipe make a difference? Part 2

[AndyW716]

I'm in the market soon to start adding some more go-fast toys to my Gen 2 (TMIC, HPFP internals, and AP...already have a CS intake/TIP), and messaged CS regarding running stage 1 vs stage 2 maps.

I was advised NOT to run stage 2 maps without upgrading my downpipe. I've had good experience with CS in the past, and everybody on here seems to agree that Spencer's the man, so I'd hate to believe that advising me to upgrade the DP was a sales tactic.

I can only assume that at 300+ whp, the cars of the posted dyno graphs are running tunes at least as aggressive/with at least as much boost as the stage 2 maps would.




Sooooo....why can't I run stage 2 on a stock DP? I'm not trying to max out the car and run as much boost as is possible...but, I'd like a little more gain than I've seen from stage 1 tunes/setups.

[timmcc02]

You need fuel pump internals before you worry about anything else

[speed23]

Originally Posted by AndyW716 I'm in the market soon to start adding some more go-fast toys to my Gen 2 (TMIC, HPFP internals, and AP...already have a CS intake/TIP), and messaged CS regarding running stage 1 vs stage 2 maps. I was advised NOT to run stage 2 maps without upgrading my downpipe. I've had good experience with CS in the past, and everybody on here seems to agree that Spencer's the man, so I'd hate to believe that advising me to upgrade the DP was a sales tactic. I can only assume that at 300+ whp, the cars of the posted dyno graphs are running tunes at least as aggressive/with at least as much boost as the stage 2 maps would. Sooooo....why can't I run stage 2 on a stock DP? I'm not trying to max out the car and run as much boost as is possible...but, I'd like a little more gain than I've seen from stage 1 tunes/setups.

You absolutely can run stage 2 without a full downpipe as long as you have internals. May just have to tweak wastegate values a bit.

Also, the maps being run in the OP are WAY WAY more agressive and would be running a ton more timing that a stage 2 map. They are safe because those guys are running e85 blends.

[Mike@Stratified]

The basic requirements for most stage 2 maps are HPFP internal and omission of 1 catalytic converter. Get a test pipe and you don't have to replace the DP to meet that requirement. I can't speak to CS's OTS maps however, so if you want to run their map, you need to do what they say I suppose.

[macdiesel]

Awesome info stratified, especially since I'm new to the mod path and the risks of a dp install made me weary. Now I know. Thanks lex and mike.


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[jdspeed3]

Here are my logs from ENM, BNR on 93, as promised.

[ihasmazda]

Everyone seems to only look at the peak numbers, but no one really mentions the power curves. After I installed a catted CS DP last week I noticed a big difference in power at lower RPM. Now I can hear and feel the turbo spooling up just after 2000rpm (about 400 rpm sooner than before) which lets me keep the car in a higher gear while cruising and made it a lot better to drive conservatively as I don't have to downshift as much. Maybe it's more due to a stg1 to stg2 map change, but the overall feel of the power delivery is significantly improved, even if the peak numbers may only be slightly increased. I guess if all you're looking for is drag racing power then it might not be worth it, but I'm blown away how much better the car drives normally, not to mention the increase in power when WOT.
It would have been interesting to observe the difference if I had gotten an e-tune before the DP install to determine just how much of the gain was map vs DP, but with a DP planned I wasn't going to spend money on an e-tune beforehand.

my two cents

[mazdaspeeding]

Originally Posted by Mike@Stratified It is true that there are a lot of inexpensive options out there for a long catless DP, and the quality of some is pretty good. Adding a cat though, for those of us that have to deal with emissions, adds cost. For me the 8hp difference just wasn't worth the trouble or money. For someone debating about upgrading to a 3-3.5" intake versus a DP, or an upgraded IC versus a DP, I think this will help make decision a bit easier. Incidentally, whenever I get around to strapping my BNR on the car I plan to see how far I can push the OEM DP and CBE before upgrading as well

^^This. I am planning on doing the same thing. BNRS3 with the stock DP a TP and stock Cat-back. I understand an aftermarket DP would help but I still expect to achieve noticeable gains running a TP only. What do you expect from this combo? (Personally, I'm looking for a slight increase in power, but more specifically to stretch it out further over the rpm band and negate the instant TQ plateau that the tiny KO4 delivers and the resulting loss of traction in 2nd and 3rd when I hammer it. Basically, I expect to go much faster with only a minimal peak increase in power but by bringing in the TQ slower and pulling harder, longer up top.)

[Big Dog]

I'd be a test car if mike wants to through in a free e-tune. Lol.

I'm currently rocking the testpipe and next month have plans to buy the CPE Downpipe and I'm debating the MagnaFlow CBE. But for testing purposes I'd be willing to hold off on the cbe.
@Mike@Stratified; you guys still offer fluff tunes? It would be great to get real comparisons and on a street car running pump gas.

[omgvance]

Great write up @Mike@Stratified;

[chaser27]

I think sometimes people get confused about what we mean by DP. Being that most (I assume) go with a full "long" DP when they upgrade, they see a jump in power from the stock DP AND TP. Your comparison is between just a TP and full catless DP's. From the people I've talked to, they understand that the majority of the benefits come from getting rid of the second cat. I'm afraid people are going to look at this, fail to read more than the title and assume both a DP and TP are worthless.

[youngwonder]

I just bought a full CP-E catless DP from somebody. I'm glad I got a brand name DP for an excellent price, but I'm sure I would be just as happy with one from ebay. I really would like to get on a dyno before it's installed.

[jbmazda6]

I will be looking into the differences in a dp as well. There will be before and after dynos and I will try to have the same ambient temps. Here is the link to the thread i created. There will be more comparisons done as well. JB's Journey with JBR and Stratified

[Big Dog]

Every test is on "E" I would love to see just pump gas results.

[jseams]

Originally Posted by ihasmazda Everyone seems to only look at the peak numbers, but no one really mentions the power curves. After I installed a catted CS DP last week I noticed a big difference in power at lower RPM. Now I can hear and feel the ...

The OP has complete dynos from all cars and the curves are virtually identical. He didn't just post peak numbers. The differences are so minor that it wouldn't change your "seat of the pants" experience.

[chaser27]

We need stock, TP only and full DP curves. I think we all agree that the margin between TP and DP isn't all that great. The difference is in the second cat

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[Boostin'likeAboss]

looks like my catless long dp will be staying in the garage until I swap the turbo lol. I'll be happy at 300awhp w/ a test pipe until my stock turbo shits the bed

[ABOSWORTH]

I've been looking forward to this post. Thanks Mike! Coming from the WRX platform where a DP is one of the best mods you can add, I naturally planning on getting one as one of my first mods. I'm glad I like to read because I saw the Lex thread and many other posts saying that the DP isn't as great of an upgrade on this platform.

[EcKid1974]

I too just put in the CS DP and it has the catted RP on it and I can tell the difference in power I can only imagine what a tune and e85 would do for me. Even after reading this thread I would still get a DP I love it and the install wasn't as bad at least for me.

[Lex]

The other things to remember is that if you install a DP and you don't adjust the tune, the boost response and overall boost will change (go up).

The sheets Mike posted however are cars that were tuned to as much as they could make in each configuration.

[Fjager]

I didn't see a STOCK dp vs upgraded DP at same boost levels comparison. With all the info and data on downpipes it seems like power under the curve is the real benefit of a DP. The graphs in the first article show that g/s was held higher for longer than the catted one. Even though max g/s was only 5 at the top end, in the middle it was much more than that.

[scubasteve711]

eventually when I have the chance, I'll post up the differences for my car - I've had an ebay pipe in my basement for a year now probably. I've been pretty lazy about putting the DP in because I know its going to be a good bit of work for a questionable gain over already having the TP. Personally i'm more looking forward to getting a meth kit put together and installed...

Great post and thread!

[bigspender]

I went stock dp and test pipe. I am getting an etune and will post up my #s when done.

[Jtaylor]

I will still take my catless DP over stock any day considering how it felt after install.

[iammike]

Originally Posted by Jtaylor I will still take my catless DP over stock any day considering how it felt after install.

I'm in it for the sounds. lol Oh, and the smell...and fire spitting...and and leaving clouds for people behind me!

[Jtaylor]

Originally Posted by iammike I'm in it for the sounds. lol Oh, and the smell...and fire spitting...and and leaving clouds for people behind me!

Exactly. All of these people claiming increasing flow for turbos make's no difference it spool time or power. SMH

[chaser27]

Originally Posted by Jtaylor I will still take my catless DP over stock any day considering how it felt after install.

Originally Posted by Jtaylor Exactly. All of these people claiming increasing flow for turbos make's no difference it spool time or power. SMH

I'm confused? Trolling?

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[Mike@Stratified]

Originally Posted by Jtaylor Exactly. All of these people claiming increasing flow for turbos make's no difference it spool time or power. SMH

If you have proof to counter my claim in the original post, please share. The dynos in the OP tell the story on power. As for your other comment, you might be the first person ever that I've seen concerned about spool time with a K04.

Sent while Stratified.

[iammike]

Originally Posted by Mike@Stratified If you have proof to counter my claim in the original post, please share. The dynos in the OP tell the story on power. As for your other comment, you might be the first person ever that I've seen concerned about spool time with a K04. Sent while Stratified.

I would rather that bitch spool a little slower...at least at the low RPM's. lol WTB tracshun.

[jack_hammer]

this is a good post to keep these things fresh.

however, i thought it has been long established that the differences between a stock DP & test pipe and a catted DP are negligible. and, on top of that, the differences between a catted DP and a catless were exaggerated.

maybe i'm assuming new members read old posts.

glad to see a refresher with quantifiable numbers included in a single post. i respect stratified for their recurring efforts of putting out informative-only posts without selling something.

keep it up!

[chaser27]

The only thing I worry about is that with so many full DPs on the market. People are going to read the title of this thread and assume the test pipe doesn't make a difference either.
This I don't care about until they start trying to spread misinformation to others.

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[spdandpwr]

Wish this was done on the same car. Not that my anecdote is scientific, but as someone who when from a @superskaterxes; tune with intake, sri, and cbe to that same tune with a catless dp and step lower sparkplugs, I felt a huge difference. To gauge the difference, I used a car race as my control. Before I was neck and neck. After catless dp, I pulled a car length with each gear. After a revised tune, I pulled slightly harder still.

[Jtaylor]

Originally Posted by Mike@Stratified If you have proof to counter my claim in the original post, please share. The dynos in the OP tell the story on power. As for your other comment, you might be the first person ever that I've seen concerned about spool time with a K04. Sent while Stratified.

Yeah give me a few seconds

[jack_hammer]

Originally Posted by AndyW716 I'm in the market soon to start adding some more go-fast toys to my Gen 2 (TMIC, HPFP internals, and AP...already have a CS intake/TIP), and messaged CS regarding running stage 1 vs stage 2 maps.

wait, so you contacted corksport to find out what OTS tune you should run on your cobb tuner?

[scubasteve711]

You all are convincing me to put my DP on... For the sake of logs...

Currently running a just a TP with stock DP off the turbo.

[Jtaylor]

Originally Posted by scubasteve711 You all are convincing me to put my DP on... For the sake of logs... Currently running a just a TP with stock DP off the turbo.

You won't regret it.

[jbmazda6]

I will have legit dyno backed info soon. Cpe full catted dp has been ordered.

[Mike@Stratified]

Originally Posted by Jtaylor Yeah give me a few seconds

I'd love to see your data.

Originally Posted by Jtaylor You won't regret it.

No doubt he won't regret it. I'm not arguing that installing a DP is something people will regret, I'm arguing that it isn't the end-all-be-all mod that some people make it out to be.

Originally Posted by scubasteve711 You all are convincing me to put my DP on... For the sake of logs... Currently running a just a TP with stock DP off the turbo.

If you can get before and after logs in similar conditions on the same road I'd be really interested in seeing them.

[bshotts422]

I have to Cobb dp with the speed daddy cb and I love it. Car sounds amazing as long as you don't mind some noise. I fucked up by not getting tuned right away and think that helped caused my ko4 to shit out. But shit happens and we learn. Now I have have a BNR S3 on and doing my tune with @Lex; now. Really looking forward to the numbers I'll be getting. @JgamB; is running similar setup and got to take a ride in his car and I was very impressed.

[xx5PEEDxx]

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