True Dual Sizing

[tinman]

I am going to redo the Exhaust on my 99. It has dual flowmaster 50 muffs with 2" pipe out the back. I would normally leave it alone but A friend who owns a muffler shop owes me. I want to replace the 50's with the 40's and add a crossover the only thing is what size to run out the back. The truck has a 4.8L. I thought that I should leave the outlet at 2". My friend at the muffler shop want to up size to

2 1/2" pipes out the back. I am concern about back pressure. I have heard the these motors need a certian amount of back pressure to run well. The Truck is lifted and I don't want to loose to much torque. I would like the truck louder and I never like the original install of the dual exhaust. I came that way from the dealer. So my only real question is what size to run from the muffs to the rear of the truck.

[black00chev]

2" sounds a little small, maybe do 2 1/4".