Hi there steve hudson and the prince!!! i am a new member and i have a honda vtec 1.6i civic, i have recently replaced my original exhaust with a 63mm Piper exhaust sytem! i dont know much about honda exhausts or a honda in particular thats the reason why i joined... what i do understand is if you want BHP on your car you need to remove all restictions from the manifold to the exhaust this means, a 63mm exhaust stainless steel or mild custom built with the bends no creases to suite you car no couplings, just on your standard manifold with two silencer boxes. you sould get get the correct air exhaust flow out and good intake which would also save you some money on fuel.