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rodhog · 08-07-2006, 02:06 AM

all I'm going to say is what I've known for years with small 4's

bigger is better.
IMO min is 2.25 inch under 2L and 2.5inch upt to 2.5L min

mandrel versus crush- depends on diameter, motor and path.

we always ran 2.25inch crush on the gemini - as well if you knwo gemini exhuast not too many bends. one day the motor was at it's peck basicly I suggested maybe bigger exhuast guys though nah man it's okay. But we had done a cam etc all required more air to get out at hi-revs. I saggested we remove the last section before the diff. The difference was amazing.

yes car's need back pressure if your after economy. You run your car when you need power on most engines in the top end range. This is why you need larger piping.
On some motors take ford 4L OHC note they never have fitted large pipes even on sport models. they are tiny but cats and mufflers flow well. This is because it does not rev it flows and yes a big improvement when you do but It's low end car so improvement is there but compared with small 4's it's nothing.

To make more power you need more air in and exhaust out.

the only thing stopping us from putting the right size pipe is noise polloution. even I would rarther fit a nice 4inch titainum setup so my baby turbo can breath.

08-07-2006, 02:06 AM	#27
rodhog Senior Member Join Date: May 2005 Location: Sydney Lakemba Car: mx-6 626 Gs300 Maz2 was 95 KF BA-HT Posts: 2,024	all I'm going to say is what I've known for years with small 4's bigger is better. IMO min is 2.25 inch under 2L and 2.5inch upt to 2.5L min mandrel versus crush- depends on diameter, motor and path. we always ran 2.25inch crush on the gemini - as well if you knwo gemini exhuast not too many bends. one day the motor was at it's peck basicly I suggested maybe bigger exhuast guys though nah man it's okay. But we had done a cam etc all required more air to get out at hi-revs. I saggested we remove the last section before the diff. The difference was amazing. yes car's need back pressure if your after economy. You run your car when you need power on most engines in the top end range. This is why you need larger piping. On some motors take ford 4L OHC note they never have fitted large pipes even on sport models. they are tiny but cats and mufflers flow well. This is because it does not rev it flows and yes a big improvement when you do but It's low end car so improvement is there but compared with small 4's it's nothing. To make more power you need more air in and exhaust out. the only thing stopping us from putting the right size pipe is noise polloution. even I would rarther fit a nice 4inch titainum setup so my baby turbo can breath.