So I've been getting some crappy gas mileage and my exhaust note has been off ever since I've installed an Invidia S-pipe/down pipe. Jacked up the car today and took a look underneath. Seams there's some moisture escaping between the s-pipe and mid pipe at idle. I'm sure there's even more escaping while the car is in motion.

I tried to tighten it but there still is a rumbling noise and still moisture escaping. Do people typically run a gasket here? Since it's a stock mid pipe and Invidia s-pipe (I believe they are 60mm), then I'll need to get a 60mm gasket..?

 

I know the our cars are screaming at 2.6k to 3k rpm's at highway speeds, but could a little exhaust leak like this decrease the gas mileage greatly?

 

you have a exhaust gasket between the midpipe to where the s-pipe meets,ands did you reuse the donut gasket

 

An exhaust leak after the header will not cause such a drastic drop in gas mileage, it has to be something else. Gaskets should be between the pipes and that should stop leaks, but any bent or misaligned part due to damage or build quality may cause the small leak. Could be the header is warped or loose, so check that first if your gas mileage really dropped unless its you driving harder from the goodie install.

 

I didn't even notice the gasket on the stock down pipe. was nicely rusted on there lol hopefully this should fix the leak. thanks for the tips monkey!

 

Lol no problem let me know how it goes.

 

Eh, placed in the gasket. was a pain to get it to line up right, as it just laid on the stock down pipe. on the new megan down pipe, there is no where to place it (flat design), I had to try my best to line it up everything. Sounds better though! thank you all