I installed a downpipe on my car yesterday and was quite surprised at how much the overall sound of the car has changed. I'm running an Invidia N1 cat-back and a Megan 3" downpipe with the stock cat (to be changed out for a 3" hi-flow cat next week). My expectation was that the exhaust note would get a little louder and a little boomier. Instead, the boom at 3500rpm was greatly reduced, while WOT got a little louder. I'm so VERY happy with both of these effects.

The turbo sounds completely different... more deep 'woosh' at max boost, instead of the 'tea kettle' sound. I'm not 100% convinced it isn't some minor exhaust leak on boost, but I don't think so. I'm assuming it's the wastegate opening. It sounds a LOT different from stock though. Is this normal? Did other people notice this effect?

Also, I couldn't seem to get the stock spring bolts to thread back in no matter how hard I tried, so I eventually just used the bolts that came with the DP kit. I assume that since the donut gasket is bigger and longer, it's not possible to reuse the spring bolts with the Megan setup. Is this correct? The pipe has a flex section, so I'm not worried about engine roll.

This pipe is great. There's a good 1/2" of clearance to the lower chassis braces. No shimming was required at all.


Rob

 

The stock cat hinders the performance of the 3" dp.

 

Yeah, I realize that, which is why I'll be installing my 3" hi-flow soon. I need to get flanges welded onto it first, etc.

But, back to the question about the sound of the turbo when boosting...

 

Mine did sound quite different. It changes even more when the A/C is on for some reason.

 

what your probably hearing is the increased resonance of the turbine side. Now that you have a bigger pipe, the turbine spooling and the overall exhaust sound should be slightly louder and deeper. Theres to much involved in sound production to really pinpoint what your hearing and why without being there to check it