RE: viper 500 servo question.
must have a 350 chev motor to get a Scat Cat to go 140.
On a Viper any servo that fits will work fine, wanna spend more than 10 bucks a servo? you will get better centering and maybe the model will hold trim a little better. that's what spending the big bucks will do. Any sport servo will do fine. I notice a differance when I use the 20 some dollar servo over the 10 dollar ones.