Just installed a yank ST3500 and it launches great, there is no chatter or locking up problems. The only thing is the 1-2 shift, when it shifts into second the car hesitats real bad and then after a little less than a second it starts accelerating real hard again. Also installed headers at the same time if that makes any diffrence any help would be greatly appreiciated... <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

 

Getting that "nosedive" on the 1-2 shift? Very familiar to me until I figured mine out. Chances are you are either hitting the rev limiter or experiencing torque management.
I was banging the rev limiter in my case, it took a BUNCH of Autotap runs monitoring just current gear, rpm & timing to catch that sucker. I ended up raising my rev limiter and the problem seems to be solved, although I occasionally experience a fair amount of TM.

 

Probably TM if you don't hear anything. Borrow an HPP3 and try adjusting the shift down 1 mph or raise the rev limiter 100 rpm and see if that helps.

 

Thanx...TTT