aftermarket header collector & exhaust diamater???

[austrian type-R]

I am in the market of buying and Exhaust system. I like alot the Taitec header and the light weight parallel exhaust system. Safing about 30kg is equivalent to 5hp . But whats about the gain in hp? If the oem cat fit, there must be the same collector diamater than stock, isn't that a bit of too much bottleneck again? Whats the pipe diamater of the oem 91 NSX? Anyone know the diameter on the aftermarket headers? Whats the diamaters on stock and aftermarket exhaust?

Thanks

 

[j14nsx]

I don't the answer to your questions, but larger diameter pipes isn't always better.