Its going on a 5.3 vortec.

 

I recommend a Transgo shift kit tailored for your application in addition to a tune if you want firm, crisp shifts and long converter clutch life.

Others on here like the Sonnax kit and various particular pieces to enhance performance and reliability. Some searching and reading will get you more detail. You're replacing a huge 12" factory converter with a 9.5" unit with vastly different characteristics. You want to tailor your valve body to be compatible with the new converter for best results.

 

So i installed a corvette servo on my 4l60e tranny and the first gear takes forever to shift. Sometimes i must let go of the gas a bit so it change change gears. Did i do anything wrong?