Adding mufflers and backpressure

[dzwestwindsor]

Hello, I have a 1971 Chevy C20 with a 350 motor. It has stock manifolds with a 2 inch outlet. I'm assuming all the pipes have a 2 inch diameter. It also has glass pack mufflers.

I'm thinking of swapping out the glass packs for turbo mufflers, because the glass packs are a bit too loud/old and rusted out.

Will switching to turbo mufflers cause too much back pressure to an already small (2 inch) exhaust system?

I'm thinking of getting either the Flowtech Raptors or the Thrush Turbo:
http://www.summitracing.com/parts/bi...0flt/overview/
or
http://www.summitracing.com/parts/wlk-17704/overview/

Any feedback about my situation would be very much appreciated, thanks.