I have a 2004 Mustang GT with 36k miles and it has been supercharged for about 6k miles now. The problem is whenever I get on it on the 3rd gear and 4th gear shift it won't shift... It sit's there and bounces off the rev limiter to the point I have to let off the gas and let it shift before I can get back on it. Is this the transmission or could it possibly just be the tq converter? btw this is an automatic transmission.

 

you should not let it shift at WOT into overdrive. mine had problems shifting as well. it got real lazy, mine bounced off the limiter till i lifted on the peddle for the 1-2 shift and 2-3 shift. the cheap way to help alleviate this is to do a J-mod on the valve body. that will allow more fluid to move and make your tranny shift harder and faster. i replaced my whole tranny 6 months after i put the blower on. mine still worked i just didnt like the fact that i had to lift the peddle before each shift.

 

Ya I have to do the exact same thing.

 

i bought a street/strip performance automatic tranny and had a tranny shop swap in a stronger input shaft. i gave them my old working tranny for labor and parts.

 

where did you buy your transmission from?

 

i went through brothersperformance ebay store. i think its cheaper on summit though

 

The problem you are having can be helped with a tune. I was playing around with some of the tranny settings in sniper software and had the same thing happen, I ended up going back to stock shift points with firm settings and the problem went away, I think it had to do with the tune trying to raise the stock rpm shift point.

 

my shift points were set at 5900 and rev limit set at 6100. overtime the car started hitting the rev-limiter.