I'm looking at a new exhaust system for my 400 DFI engine, it has AFR210s and a 240/245@50 .594 lift solid roller. I've seen this rule of thumb "115cfm per square inch of cross-sectional area you need 2.2cfm of flow capacity per horsepower". It shows that you need a lot more than 3" for 500HP and over. Do you really need more than a 3" exhaust?

Cheers

 

Uhhhhmmmm, yah, with 500hp, you will need more than 3" of exhaust.

Best to go with a single 4", with 1 3/4 or bigger headers (with 3" collectors)

 

Yes, go with a single 4"

 

4" for sure..... and get the Magnaflow if you order from Hawks. It sounds killer.....If you don't mind pissing off the neighbors.

 

OK thanks, so that rule actually works pretty well. It will have to be a custom build unfortunately, whilst the exchange rate is pretty good at the moment shipping costs to New Zealand are pretty high :-)