Last time, I ran 2.5 inch straight through, I never really got good performance.
Andrew D, ran 3inch up until axle, and 2.5 inch over the axle for ~180kW (from memory)
I'm running 3inch mandrel this time.
I might HAVE to run 2.5inch mandrel over the axle, due to the modified rear suspension.
Stainless mufflers are a good idea for everyday city drivers. But for weekend users, a mild steel system is the best "exhaust note" option.
Titanium systems are for tossers with too much money, or for 11/10th effort racers.
I've already made a mild steel dump/front pipe, and am now looking for ways to squeeze a cat and 2 mufflers on my 1200 sedan. Cost $70. On a modified turbo system, getting the dump pipe right is critical. My turbo has been moved 15cms forward, so I can run a 45deg angle to under the car. It's a much better solution that the ~90deg bend most Silvia dump pipes do. The rest of my system will cost about $250 for the 3inch cat, and $250 for mandrel bends, $300 for mufflers (2 of) also need a hotdog resonator. Turbo engines sounds buggered with no resonator and only a straight through muffler.
So I'll run:
3inch dump/frontpipe
3inch cat
3inch hotdog
3inch straight through Lukey
3inch N1 style rear muffler 4 inch tip ( no leaf springs

)
Go and make some friends at an exhaust place, maybe they can get you some second hand stuff from a new low kays car. 2.5 inch would be fine for a budget system.
Cheers,
Chris
ps. dump pipe pics at
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