From what I know, you can tune a 90. All you get though is 110. So you pay $700 to get a 20hp bump but, that same credit will give the 60hp a 50hp bump. No matter what, it will not go over 110, thus I see it as a rip off for anyone that owns a 90hp and buys it would thinking you now get 150hp. Nope..110You can still tune your 90. ???