How about having FLT upgrade your level 4 to a level 7? They did my level 7 about 4 years ago and put a t brake in in. It is the most reliable part of my car. I launch with 5psi of boost and go 9s then drive home, 200 miles round trip. My car weighs 3850lbs.

Yeah that is an option as well.

I just want to leave hard off the line as I finally have a 9" rear to beat on. So was thinking the t-brake would help to stall up and improve my 60'.

Ya the tbrake is awesome. Kind of expensive becasue you need a moroso trans pan thats like $250 bucks. But worth the money for sure.

my 4l60e I foot brake and have 1:40's to 1:50 60's on 275 60 ET street radials and 3:55's

You don't need a trans brake too stall a car up, see post 18. You need more converter and more rear gear.

I hear ya, but car is mostly street driven with occasional track use.

I did step up to a 3.90 gear from the previous 3.73's. Also added a bit more power so we'll see how it goes next time out.

A turbo 400 has a first gear ratio of 2.48-1, lower
A 4l60e has a first gear ratio of 3.06-1, much higher, and will hit harder than the 400 with the same rear gear. A trans brake will not allow you to launch harder, it simply holds the car on the starting line so that it will not roll.

http://www.magic-photos.com/2011/Sun.../DSC_1459.html
4l60e