Yep, I have a friend with a performance shop. He had a mixed bag of used silencers sitting around that he let me take home and try out. I ran it against my Dad's identicle Viper leaving his alone. Every single one I lost power. Rpm's went down and he pulled me badly in 1000' runs. All I had to do was install my stock can again and I was right there with him again. The ones I tried were SLP, Bender, MBRP....the three most popular. I never tried the Sno Stuff , Maxx Perf./Hauck or the PPE. I wouldn't expect much difference. I do remember over on Rich's site ,**********, a guy saying last year he had the Bender single and the Bender silencer. He claimed the whole package was slower, but if he ran the single into the stock can it was a bit faster.