mufflers or no mufflers??

thanks for all the replies and info. I dont know why it says my first post because i have had several posts just not in the last 2 months. but ne ways hi to everyone.i have str8 pipes to the muffler on each side right before the rear axle. no x pipe.

parts on the motor:
kb 10:5:1 pistons
balanced motor
melling high flow oil pump
mild port on the heads
roller rockers 1:5 ratio
all new valves etc..
ported elderbrock manifold
demon 750 double pumpr
erson cam 510 lift
solid lifter setup
stock manifolds
electric 112gph fuel pump w 5/8 lines
msd 6al w/pro billet magnetic distributor