I have recently dropped a 4.1 into my originally 3.3 xc falcon and now doing the exhaust. What would be the best size to have it all the way through? I have just bought some cheap extractors off ebay, so that's covered. Thanks.

well hey come out with a 2" pressbent system with 1 muffler.

personally I made a system bulkly out of 2.5", and 2 1/4" at the end, but that was budget restricted, e.g. what pipe had lying around, it's nice on noise, but could do with a rezzy badly so either 2 1/4" or 2.5".

Probably 2 1/4 My system I built for clearance though. as my cross members 80mm off the deck, the day I lowered it Drove over a cattle grate at a farm and pulled it straight off.
I'll admit having a lowered car regularly in situation like that isn't suggested but what you gonna do.

So 2" 1/4 or 1/2? Definitely not 3" Yeah the car is lowered too so I am going to have to make sure I don't do the same. Not the best for some situations. But worth it for the drive and looks.
Cheers mate.

Yeah, haha, unless turbo'ed or supercharged etc. no way on 3"

2.5" mandrel bent. from the extractors right back to tail pipe. with a nice exhaust tip. and one big muffler

2 1/2" it is. Thanks guys.