My 69 Charger R/T currently has exhaust manifolds and 2 1/2" exhaust with cut-outs and a H pipe. I have headers with 3" collectors. Would I be losing a lot of power by keeping the 2 1/2" exhaust? If I install all new exhaust, what should expect to pay an exhaust shop, not including cut-outs and mufflers? Should I have a h-pipe, x-pipe or neither? The engine is almost stock with a 272/455 cam and Performer RPM intake/770 Street Avenger carb. Thank you in advance for any insight!