MY YARIS IS SLOW NOW?????

[ChinoCharles]

yes it does affect your high end... but its great for racing and drifting...

-slaps forehead-

Listen, here is the deal... with exhausts on your Yaris... first of all, you guys are still running a stock midpipe right in the middle of your system. You'd probably see better gains replacing the header and midpipe than you would the header and axleback portion. The key is to "get it out." Running 2.25" piping for the first 50% of your exhaust will free you up... running 2.5" piping to 2" piping then back to 2.25", that is just crazy. If you expect noticable performance gains from that kind of a setup, you're crazy too.

If you really want a performance exhaust on your yaris, get a header, trick the sensors in the midpipe and run a test pipe. Otherwise, you're only doing it for looks and sound... not that that is bad, I'm just trying to keep it real. You definitely want to open up that midpipe.

Second of all, the most likely scenario when adding a larger diameter exhaust is that you will lose some low end power unless you're doing something to get more OXYGEN into your cylinder and you are running a FUEL PRESSURE REGULATOR to get more fuel into your cylinder. Only when you have more AIR and FUEL in the cylinder will your engine begin to make enough power to justify the larger exhaust at low RPM's at make it work for you under 3 grand. The good news is you will inevitably gain on the top end. Above 3000 RPM your engine is producing more and more exhaust as you rev higher, and the larger exhaust tubing will help you in that situation. Backpressure is your enemy at high revs, your friend at low revs.