S16 exhaust options

[miles]

Your right the 6 manifold use's different port spacing and shape along with 1 stud being different too, Not allot can be done other than replacing the manifold as the cast iron one is restrictive coming from the old 1.9 base engine it was just done to be cheap at a guess. I do a 4-2-1 manifold for these but it's not cheap to the low demand of them at £400.00 in mild steel, Without knowing the spec of engine etc any gains are hard to say but with a basic tuned engine, T/B's, Reground cam's these see a good 10bhp gain along with mild range torque