Best exhaust size and options, 02 L200
 

So I bought a l200 used with an exhaust leak... With my wife finding employment I am making the call on fixing the exhaust before she drives it daily so that she doesn't suck carbon monoxide and asphyxiate... But I can't help but do something right, or at least as close to right as possible... I figured while I am under there, might as well upgrade the entire system... I have a couple questions though...

What size exhaust works best with the 2.2 L61 four cylinder? I have gone by the rule of thumb of 2.25 inch for a four cylinder engine, but most stuff for he l61 on zzperformance is 2.5 inch, is that a good size, given the car is an auto?

I plan on having it custom bent from the exhaust manifold flange to the end of the tail pipe (brake bent, which is better than crush bent like what is there now, but not as nice as mandrel bent), using a universal high flow cat, (cheapest i can find), possibly an o2 extender to make the car play nice with the cat, the longest glass pack I can find to replace the half rusted resonator(I found one 41in overall length), and I'm not sure what muffler... The options are as of now either a thrush turbo muffler, or a half decent looking fart can i found( apexi I think) I am leaning toward the thrush and a chrome tip, halfway stock looking, lol

Am I on the right track? Or at least not too far off? It needs to be civilized at idle and cruise, and I would like a nice tone when I step on it... A power/FE improvement would be a plus...

All opinions welcome...

2 inch all the way back.

You can go 2.5 all the way back on any ecotec, but 2.25 on a stock rig would be better.

the bigger the exhaust pipe the slower the exhaust moves. Slow moving exhaust has more pressure. You want the exhaust to move fast and stay hot. Hot gases are more fluid have less resistance and weight. Bigger is not always better. A bigger pipe allows exhaust to cool and then it gets heavier providing more Resistance moving down the pipe. Here is some interesting info to get started.
Formed Collectors, hand built Custom Collectors, Street Exhaust Hookup Cones, Megaphones

If the right taper is put in there the exhaust really accelerates.

here is a calculator that shows what size pipe you need for the horsepower of the engine. A saturn SL is good with 1.75 inch pipe
http://www.mk5cortinaestate.co.uk/calculator5.php

You're getting through just fine, Andy. I don't know if bones still has that car or if it's the one he's parting out.

Ya, L=history