Engine masters basically dyno proved nothing is too big when it comes to exhaust or headers. Just that increases get smaller and smaller with bigger pipes. Personally if you plan to keep the 305, I'd run dual 2.5" If you plan to go with something bigger later, why not go 3"?
I went 2.5" on my car because I wanted a side exit exhaust and pypes only makes it in 2.5" (a very nice kit, and I am happy with the install, fit, and sound)... just wishing I had gone 3" not and payed the price for a custom exhaust.
Thank you, pontiacgp and drogg. And Pontiacgp, do you have any sources or knowledge bases that you wouldnt mind sharing so I could so some reading, like how you reasoned that the necessary pipe diameter for a given engine size and how much gas its putting out in cfm is 1 5/8 pipe? Or are you just a physics master lol. You seem like you know your stuff brother
thanksI'm a major psychotic but a master of nothing....there are plenty of links to help you out with the size an engine reguires
http://www.mk5cortinaestate.co.uk/calculator5.php
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