3.0" Downpipe - Unexpected Benefit

[JohnM]

Wow - I didn't expect this benefit. My gas mileage seems to have improved by over 20% with the addition of the 3 inch downpipe and CAT. Admittedly this is after just one full tank since adding the downpipe, but that first tank is almost 2 mpg better than my best ever. I have averaged about 17.5 mpg over the life of the car with combined daily driving. I've checked almost every tank in 10K miles, and it's usually between 16.5 and 18.5. Best ever has been just short of 20 mpg and it's only been near there a couple of times. First tank with new downpipe is 21.8!

BTW - I noticed no increase in mileage with just the addition of the 2.5" Mopar/Borla cat back system before I added the downpipe.

I've got the Maxxfab downpipe from Scottmech. See his post in the Vendors area for pictures of my car with the pipe.

[Culprat]

That's great JohnM,I have order one based on the photo's
that you posted and talking to Scott.

[dfunkdj]

Whod 3" down pipe is it ??? Did you use both o2 sensors??

Don

[JohnM]

Well ... the second tank wasn't as exceptional as the first. It was 19.1 mpg. There wasn't a big difference in the the way the car was driven - perhaps a bit less freeway. In any case it's still a clear improvement in mileage with what's looking like it may be a solid 10% gain on average.

Otherwise, the car drives great and I've had no problems with the downpipe and cat whatsoever. If you've got the Mopar cat-back, the 3" downpipe and cat will definitely increase the exhaust note. It's still less than being loud for everyday driving, but it won't be confused with stock.