The custom/aftermarket exhaust thread! [Pics + Videos]

[malibuguy]

Originally Posted by j-san

A question for you exhaust gurus:

A search of the forum turns up conflicting reports of a freer-flowing aftermarket exhaust system improving/hurting MPG. Some said it improves MPG and power, others have said it hurts MPG, but improves power. Either way, it seems a better exhaust will improve power and possibly affect MPG.

I drive with a fairly light foot and mostly on the highway and average 43MPG most days. My Yaris is stock, but I am open to doing an aftermarket exhaust, provided it doesn't sound like bad rice and seriously hurt MPG. I wouldn't mind the few extra HP for a little help in the passing lane. If I go aftermarket, I plan to leave the intake stock and drop in a K&N filter. Maybe a header is fine, but I plan to leave the cats and resonator intact and possibly add an additional resonator after the stock one. There is a local custom exhaust shop that can do the work and I would ask them to follow the stock piping, but go up to a 2" pipe vs the stock 1.75" pipe (I understand the cats and resonator use a 2" pipe) and route it to the factory flange at the rear axle. From there, I'll probably bolt on a Tanabe Medalion or Nitto (plan to buy from Micro Image) as those two seem to be the quietest mufflers. How does that sound for an exhaust set-up?

I am not expecting oh-my-god gains in HP or anything, but hope to have a little of both worlds: improved HP while being able to retain (or improve) MPG.

To be honest. Keep the stock exhaust for mpg. I usually have run about 3mpg less with my exhausts. Most of the fact that I love to listen to my exhaust. Plus the stock exhaust is better matched for low rpm performance.

A typical muffler shop will only crush-bend tubing. So their 2" tubing is typically smaller in the bends then your stock midpipe. So the only thing your getting is no improvement in exhaust flow and lower quality tubing that will rust out eventually.

I suggest a rear section exhaust for some power and sound and not throwing away all your mpg.

These motors really love a full exhaust so real gains in power can be realized