DIY Exhaust Mod – Gain of 10+ HP!!!

[JAAY]

The automatic would definitely make a difference and also I have hight flow cats, headers and a totally different motor. None the less great job documenting all of this!

[chipmunk]

Changing the manifolds does make a difference. I remember EDC saying that the drone decreased appreciably when he installed free flow manifolds.

Just curious - with that configuration, would a high end performance exhaust not be better than modifying the std muffler? Or do all performance exhausts suffer from the same drone problem?

[JAAY]

I have had many exhausts and they all had drone that was deafening. The stock muffler had made the most power in conjunction with some cheap headers and good high flow catalytic converters.

[chipmunk]

Interesting - I did wonder about that. I originally thought that the drone was related to the design of the exhaust system and the materials it's made from. I have now come to the conclusion that the car - location of the engine, seating compartment, etc are susceptible to reverberation from the exhaust sound i.e. it doesn't matter what system you use - when the exhaust noise reaches a certain level you get the drone. This seems to be in line with your experience as well. Maybe this is why the Boxster exhaust is so quiet in std form...

[JAAY]

My thoughts exactly. It is what it is and there is nothing we can do about it.

[JAAY]

I just put my long tube headers on and with the 1" holes yes there is tiny bit of drone, nothing like an aftermarket exhaust at all. I had no drone with my shorter headers.