The LT's will make it marginally louder. What makes it louder is either no cats, or hi-flow cats. I installed jba ceramic LT's and mating high flow catted H. With SS FRPP FRS-500 mufflers, it was too loud, and drone at 2 k rpm. My fix for that was to weld in a pair of SS pypes M80 resonators..just before the rear axle. Problem solved.
With my small roush M90 blower (5.7 psi boost), frpp twin 62mm TB, DSS-DS, and a 94 tune..... the addition of the LT's and high flow catted H made a blatantly obvious increase in hp/tq. Another 47 crank hp to be exact. This is on a 2010 GT.
Whoever quoted you 7 hp is full of it. The LT's + high flow catted H was the best mod to date ( aside from the blower).
With my small roush M90 blower (5.7 psi boost), frpp twin 62mm TB, DSS-DS, and a 94 tune..... the addition of the LT's and high flow catted H made a blatantly obvious increase in hp/tq. Another 47 crank hp to be exact. This is on a 2010 GT.
Whoever quoted you 7 hp is full of it. The LT's + high flow catted H was the best mod to date ( aside from the blower).