6 MS6s have bad choke point in TMIC cold tube

[dale_gribble]

This is probably common knowledge but I literally had no idea after years of ownership. I have been investigating opening up my OEM intercooler cold pipe because the taper down from the intercooler flange visually looks like a choke point. I attached some pics I found of the neck inlet compared to the outlet.

I was getting ready to have my cold pipe cut and welded out to open that neck up like this guy in the pic I posted below. Then my buddy brought me an 07+ cold pipe and the thing was WAY more opened up in the neck area. You can see that here.



I found some measurements online of the 06 pipe vs. the 07 pipe.

The 06 pipe is 5.28 sq inch at the intercooler gasket area and drops to 2.51 sq inch at the pinch area and 4.91 sq inch at the throttle body end of the pipe.

The 07 pipe is 5.28 sq inch at the intercooler gasket area and drops to 3.11 sq inch at the pinch area and 4.91 sq inch at the throttle body end of the pipe.

The 07 pipe has 20% larger area in that pinch area and the pipe is generally opened up quite a bit more throughout. I am guessing that Mazda knew the 06 cold pipe flowed like crap but didn't have time to revise it before early shipments and revised it as soon as possible. It's one thing to have the aftermarket fix a problem, but you know its a big deal when the OEM revised a part bigger. This tells me I'm onto something.

I don't know how this extra flow will impact performance on a k04, but I am willing to bet it's going to make a good difference on my bnr, especially considering how opened up everything else is on my intake/exhaust. Wouldn't it be crazy if this stupid cold pipe has been holding my car back all along?

I am using my buddies 07 cold pipe, I ordered some JBR cold tubes and a Snow meth tap for the silicone tube so I can swap the setup in place of my 06 cold pipe. I will definitely post up before/afters, but my gut says there will be gains above the noise floor.

I don't know how many others with older 6 speed 6's knew this. I sure as shit didn't.