heavy exhuast runner porting.

I plan on using a 50-300hp NX nitrous kit,actually utilizing settings from 50-300, and i was thinking. I know if i port too much on the exhaust and too much exhuast flow is going to kill my low end torque, but what if i use fairly restrictive mufflers when i'm just driving around, and then maybe have an open Y pipe to let it be open exhuast when i want to run the juice or maybe use some of those, i think they're called warlocks, from flowtech. I want to get the most out of the nitrous, and i am using a comp NX274H cam. It's 274/.519" , 292/.534" 230/244 @.05". Does anyone else have any feed back , suggestions, comments. Oh yea its going to be a 430-450 hp 355 in a 72 pickup.

uuhmm.... ... i dont ..... think so..... but i just looked at a warlock muffler, and it is still a high flo muffler. But is a cut out like a Y shaped pipe with one pipe going to two; one goes to a muffler, and the other goes to a dump. Thas what i was thinking of. BUt do you think my idea would work; huge exhaust with restrictive muffler to keep low end, and then open the dump for the nitrous?