i really like my SC tuner for my girl friends car to adjust the speedo for the bigger tires-BUT-it has a problem with pinging on the 91 tune even with 93 fuel in it. SO i call super chips and ask to speck to a tech. i asked if the 87 tune detunes our cars since the 5.7's run 89 min from the factory and after speaking to 3 different tech on the phone i got 3 different answers [ yes-no-and i dont know] WTF!!!!!! THEN I TOLD THEM THAT I AM SIGNED UP ON THEIR SITE AND WANT TO DO A UPDATE ON MY TUNER BUT THEIR SITE WONT TAKE MY USER NAME OR PASSWORD FOR THE PAST 2 MONTH'S. so the person i'm speaking with trys my name and pass word and say's to me [HEY IT'S NOT WORKING] then he trys his own and it's not working either. SO i send my tuner to them [working] for a updata with a check for $12.50 for return shiping-and guess what? it comes back to me not working at all. WHEN I PLUG IT INTO THE CAR IT SAYS TO CONTACT SUPERCHIPS. I'LL never buy another superchips product ever!!!! the people on the phone side step your questions and their products have always had a problem with spark knock on every one i have ever bought for any of my cars and trucks. I'M DONE WITH SPENDING MY MONEY ON THEIR JUNK.