What size exhaust should I run on my 454? It has 1.75 inch headers and 2.25 inch dual turbo muffler's right now . Is this O.K. or should the muffler's and pipe's be 2.5 or 3 inch, any help would be awesome.The motor is around 425 H.p. and run's a Edelbrock performer. Not sure of the cam but run's very lopey.Thank's again.