Going to the dyno in about an hour. Hoping to put down 415rwhp. Combo is:

Forged 348
Ported TB
Stock LS6 intake
ABS speed 2.5 heads
Trex
Edelbrock 1 3/4 to 1 7/8 HVMC
3" X-pipe
Dual Warlock mufflers
Stock pulley

4L80E
Stock verter (waiting for my 3,200 Fuddle to come in)
8.5" 10 bolt
3.73's
275/50/15 on Riveria wheels (came with the truck)

 

I am going to say you will be lucky if you hit 400 RWHP with that 4L80E trans. Those things eat power up like its popcorn.

I predict 380 RWHP.

 

We'll see soon.. The old set up was the same except:

Stock LS6 heads
Stock TB
223/227 XER 108 made 362rwhp.

 

No clue considering I don't know how much power to estimate the 4l80 eating up. Good luck though.