i want to build a single exhaust system for my 87 rx7 gxl. i am going 2.5 but no cats and straight back from exhaust manifold. the reason is my exhaust is rusted out completly. and need to change it first. i want to know if i do this. and later get a borla header or pacesetter header, it would work with the system i built. just worked a double shift. and had to write this so i wouldnt forget. a bolt on to the new header. please pm so i get the news. and the charcoal canister i took out i ran the lines into my fender and port some holes by my right wheel. so it will air out there. is that ok. thanks

 

what I have found that works best for a non turbo using a single with stock or street porting, is a 2 1/2 down through to the catback; opening to a 3 inch, 8 inches back from the catback mounting point.

This seems to give the best mix of low end torque and still make some decent gains at top end (5K up).

as far as your custom system, I would retain the stock points for the main cat. That way any header or down pipe (except the racing beat one) will bolt right up, as well as if you get some cash later on and want to modify the system, you can do the cat back or front sections seperately.