[Esky]

Regarading the exhaust piping size, which of the following makes more sense-

1. Use a pipe of slightly larger than stock diameter between the headers and the mid muffler, and stock diameter between mid and rear muffler- the idea is that exhaust cools down and decreases in volume along the way, so we need a somewhat smaller diameter piping near the end to maintain the flow speed;

2. Use the reverse of the above and actually using a larger diameter piping towards the muffler, as I've read being done on a 400bhp drag Integra with B18C in a car modding mag. This is also a feature in one of APEXi's exhaust system design, the reason being something like slowing down the flow to match that of the boundary layer (the exhaust flows slower close to the pipe's internal surface) to reduce turbulence due to the speed difference.