well my buick has 140k on the engine tranny etc it still shifts perfect never a issue but its getting to that age where im getting nervous about adding more power without frying it. a little about the car it was my grandmas for 100k of the miles all maintanace done etc and then my mom who drives like a grandma for 20k and then me for almost 20 now. i drive pretty slow too most of the time with the occasional full throttle pass lol. do i have to worry about it?? also it has the super low gears like the 2.73 or whatever they are i am really wanting to swap those probably up to the 3.60 or whatever gears, has anyone done this swap? how hard is it i can easily see this one swap adding more fun to driving the car then even a supercharger in some ways. agree disagree?? i figured while i was in there id add the shift kit thinking this would probably extend tranny life firm shifts and less load that got to be a good thing. and for the record i rarely se extended highway time when i do i usually stay right around 75 so i dont think revs will hurt me tooo much there again thoughts?