My exhaust experiment!

[fuji]

Well I decided to try some different combinations as far as exhausts are concerned. Just a bit of background. i have a 08 Yaris HB auto.

Initially I tried a 2" crush bent - this would be bit more free flowing than the stock 1.75" mandrel bent tubing. I did not have a resonator and placed a very free flowing straight through exhaust system from Maxspeed. I really loved the sound but was surprised by the dramatic loss of low RPM torque and power. It did however free up some kick in the upper RPM range but most of the time I do not drive like a maniac. The auto transmission may have had something to do with this as well. It seemed confused as to when to shift.

Next I switched the piping from 2" crushed to 1.75" and a smaller more restrictive Dynomax Super Turbo exhaust. The torque all came back and some. I did lose all the gains on the top end though. Overall drivability was much improved in the lower RPM range where most driving is done. I am assuming the overall exhaust velocity increased and therefore the low end torque returned. One issue was the muffler I choose was very small to make sure it didn't grind against the ground when lowered.

Well, what did I learn? Our stock mandrel bent 1.75" is actually pretty darn good for those not going crazy with headers and forced induction, I should have kept mine. A less restrictive exhaust would probably have been perfect for my daily driving needs. I think the other thing that makes a BIG difference is the auto VS manual transmission. My current thinking is the auto transmission with its lower RPM shift points is not well suited for mods that only make power in the upper RPM range. If I had a manual this would be a totally different story. Much more control over the RPMs you run your car at as well as different gear ratios.

Hope my experiments help those in the future trying to figure out what exhaust will work for them