Had a viper kit fitted to my small turbo cossie last summer just after I bought it. Did'nt have a power run on the car before the kit was fitted, but was knocking out 223 horses after which I thought was pretty good for the middle of summer

Had not had the car long so performance gains were hard for me to judge

I think there were better kits out there but not many would go on a small turbo model and all were just as expensive

Having said all that I would still have anything over the standard kit