3 in exhaust on stock ls1
3 in exhaust on stock ls1 is there any hp loss if i install 3 in exhaust piping on my stock ls1 ima be runing an x pipe to bullets and headers i ask because my friend told me i might lose hp because of the lack of pressure
No you're not going to 'lose' hp perse, you might lose some low end torque but probably gain that in the higher rpms.
What that does is basically push your torque at a higher rpm, so you may lose some but you gain it back somewhere else.
Though putting a nice chambered muffler instead of a straight thru one will keep some of that backpressure in the exhaust even with a bigger diameter. So you get the best of both worlds, more flow due to the 3" pipe and backpressure due to the more restrictive muffler.
What that does is basically push your torque at a higher rpm, so you may lose some but you gain it back somewhere else.
Though putting a nice chambered muffler instead of a straight thru one will keep some of that backpressure in the exhaust even with a bigger diameter. So you get the best of both worlds, more flow due to the 3" pipe and backpressure due to the more restrictive muffler.
you wont lose anything. it will only sound different, louder with a 3 inch that is. 
