i just wanted to ask what is the huge tank on the exhaust in the middle of the car? and also is the cat connected to the exhaust manifold in front of the engine? thanks

that huge tank on the exhaust in the middle of the car is probably your resonator, it helps quiet down the exhaust noise. and since the xb is alot like the tc, i would imagine that the primary catalytic convertor is in the exhaust manifold collector.

so thats what alot of people remove when they do a custom exhaust

no, resonators don't hurt performance, catalytic convertors and narrow piping does.

if you just did straight pipes out of your xb, it would sound like $h!t, and drive you crazy.

when you do custom exhaust, on a street car, you usually want high performance, but a tolerable (preferably enjoyable) exhaust note. so you would replace it all with piping that would have greater diameter for higher flow of exhaust gases.

you're probably thinking of a cat converter

ok thanks

what would be an ideal diameter for the full piping?
2"1/4, 2"1/2, 3"

2.5 probably. 3 is for turboed, 2.25 is pretty much stock.

the diameter on the piping depends on the applications, n/a engines don't wnat exhaust that is too big, and f/i cars will want larger exhaust piping for minimalized back pressure.

ok i have another question, im gonna get one of these but i want to know what is the difference in the size of the oval? or it doesnt matter the both will sounds the same

4x9 oval
http://cgi.ebay.com/ebaymotors/MagnaFlow-Muffler-4-x-9-Oval-14-Body-2-25-C-C-11215_W0QQitemZ220229583215QQcmdZViewItem?hash=item220229583215&

5x8 oval
http://cgi.ebay.com/ebaymotors/2-25-C-C-5x8-Oval-14-Body-MagnaFlow-Muffler-SS-12215_W0QQitemZ380015815991QQcmdZViewItem

there is a big cat in that resonator

The scuba tank is a muffler. Not a resonator. Your only resonator is connected to the axel back on your car.

For some reason, Scion decided to put the muffler mid car and the resonator behind it. That is why if you were to take off your axel back, your exhaust note would sound pretty good. This is due to the fact that you still have a muffler, but removed the resonator.

The small piping in our cars is nice because it gives us plenty of bottem end power which is nice for the majority of our performance setups.

Coryjames, I don't believe there is cat in our mufflers. It should be before that large muffler on the or close to the S pipe.

its built into the mid car resonator and a muffler is a resonator just the proper term for it