well i just installed the c&l racer and x2 tune for 87 octane and i must admit , quite a bit different from stock tune. even with 87 tune it is real punchy and has more balls, or so it seems. it is fairly cold here in upstate n.y. and i didnt get on it too much but it does seem more powerful. im waiting till my tank is almost empty and then ill fill with 93 and change tune.im expecting greater improvement then. now i just need to learn how to setup the datalog aspect of the sct . by the way ,the tunes i recieved are adjustable to some extent. i have not changed any perameters as of yet but it is good to know that i can if i want. vynle.