Chevy 5.3 cold start idle (muffler delete vs Flowmaster)
TRUCK ON RIGHT STARTS FIRST
Summer cold starts, the trucks have been sitting overnight, outside temperature is 87* with 98% humidity.
Truck on right: 2011 Silverado z71 5.3 v8
GM catalytic converters
true dual 2.5" pipes
muffler delete
4x18 SS tips at 45* exits
Truck on left: 2004 Silverado z71 5.3 v8
removed catalytic converters
3" intermediate pipe
3" Flowmaster Original 40 si/do muffler (PN 430402)
2.5" tailpipes
3.5x16" SS tips at 90* exits