I put this motor in my truck about 5 years ago. Its a 99 ls1 out of a firebird with the 4l65e trans. Ran good but the was always something not just right about the whole setup. Used street & performance setup, pullys wireing harness and they had my computer programed. Well my problem was I could not tell much differance in power from the 355 tuned port motor I had in it before the ls1. I called them they said there should be no coparison. I broke 6 drive shafts and busted 3 gas tanks, needless to say it was a headack. I had it on a dyno in indiana when I broke the frist drive shaft it only turned 279 horse power. But it was running 132 in thrid gear. Busted my gas tank and I was stranded. Well it took me about 4 years to figure out what was wrong, they had set my rev limiter at 5200 rpm and when I bunped that it poped the drive shaft every time.
Well all and all I like the weight saving 150 pounds off the frount of my truck. Runs ok and gets 20 mpg but I stll think it should run better than it does. So I ordered a tunning program a cam and after the last drive shaft a 6 speed trans. I got a drive shaft built suppose to handle 1200 hp. The last one I thew out I was passing about 6 cars bunped that rev limiter and broke drive shaft, busted gas tank full of 93 octaine 53 bucks worth, and also busted my trans. On the plus side I didn't wreck doing 130 that's a good thing. So I put the new trans manual now and the cam in and programed it all at the same time and now it won't even rev above 1400 rpm. Got frustred with it,got married, lost my job, had a kid. so I parked it in the garage for 4 years now. I recently got a decent job my son is now 2.5 year old so I got it out the other day and started tinkering with it again. Still won't rev up so I have been resercing and I think I have figured out my problem. I did not take out the cam sensor when I installed the cam. So I am going to put a new one in and hopefuly I can post some times at the track next year. I won't know how to act if I do get to drive that thing with it programed and camed and a 6 speed. I can't wait.

 

Ive had one without a cam sensor and it would rev above 1400, it just didnt run right and the timing was way off. So I doubt thats your problem but its worth a shot.

 

Here is some pics of my truck

 

What do u mean you had one with out a cam sensor! How did u even get it to start?
I was talking to a few people and I was also reading in the sevice manual about a cam install and I did every thing that I was suppose 2 but take out the cam sensor. And a local gm mechanic told me if that sensor was bad it would cause it not to rev up. But I don't know ill find out here in a day or so. Ill let you know if not ill have to buy the autotap update because the old one does not like vista 64 bit at all!
Steve

 

How much Nitrous you got on that thing?

 

How did u know I had nos on it? Seen the lines and injectors huh. 150 hp shot. But I haven't even got to drive it with the cam and 6 speed yet!!!!

 

Yep seen the Line and Injectors.