Yes I installed them on my L99. It is a two person job. Sounds better. Not too loud but deeper. I can't tell on the power or torque. I'm not expert and I do not hot rod it very much. Never even did a burn out. The toughest part was loosening the bolts that connect to the headers. Put penetrating oil on the day before to help. No check engine light so far. I guess it was 650 bucks for it to sound a little deeper and maybe 10 rwhp. I just bought the subthump 5.1 totol system. I am hoping to have some better sound. Unfortunately the factory boston speakers are junk. Good luck.