After market exhaust and MPG/Torque

[rumney510]

Hi all

what effect will an after market cat back have on my MPG?? I drilled the airbox and lost about 2-3MPG, don't won't to do that again!! But gained quite a bit of low end power.

For anyone with a V8 did they get any increase in low end torque with a cat back??

thanks all
Andy

 

[RTStork]

I didn't lose any mpg with my cut air-box so I bet your loss is from you enjoying your extra power. I havent been able to test if my dual exhaust helped mpg on the highway, but it must have helped because before the exhaust, the best city mpg I got was 16 and now I'm getting 16.8-17.2 and thats with me running it harder now that i have the cool sounding exhaust! So I would definately say it helped. Now if I can only learn to take it easy to fully see the mpg gains.

 

[JDraper]

I didn't lose any mpg by opening up my air box either. On my '92 I installed a Flowie cat back system and saw about a 2mpg increase in fuel economy and a definite power increase. We have a mountain with a 4 lane over it near us, and before the Flowie I had to start at the bottom in 4th gear (stickshift) and drop to 3rd about halfway up to hold 65, after the Flowie, I could start in 5th at the bottom and just had to touch 4th near the top to hold 75. DEFINITE improvement.