A single exhaust will always produce more power because it allows for scavenging, which is a big power producer for the Rotary.This is why the 3rdgen has this setup.

Your best setup is 2" piping make it 3"s straight from the block then 4' then collect it. then run 2 1/2 piping, you can get the 2nd gen rx7 exhaust down to 1 bend after the header collecter. and put the muffler as near the rear as possible. Use a very high quality stainless steel muffler with ceramic or steel packing, eveything else will burn out within 100 miles. or blow apart from the backfire and flames that this setup produces.


I can say this is true as we made 4 different headers for my buds rotary rail and this design was the best for low end and top end power for the 6 port 13B which ran a 12.6