I've got the LT4 package. To me, it does exactly what I want out of it. Ihave a daily driver that gets 22 Highway mpg, it's fast enough for the street, and hasn't had any reliability issues. If this was a second car, I would def go bigger, and I believe I could have for the same money. This is just like any other mod for your car. You have to make choices that best suit your needs.

 

you get 22mpg highway ??? last time I checked I only got 18.5

 

With the ported heads, HOTcam, bolt ons and a tune I got about 22 mpg through an auto on the road.

 

well i been getting o2 codes and cat inefficiency codes , I have 2 o2 sensors sitting in front of me , i wonder if they are the culprit

 

I am also getting 20+ mpg with the LT-4 kit. On the highway, I can probably get better than 25. This is with an M6 though, and not an automatic.
Also, I have the LT4 kit, bigger injectors, shorty headers, 52mm throttle body, and am bored and stroked to a 383. I am only making 352 at the wheels with a custom tune. I think I may need to get a re-tune because it seems to be running very rich (stoplights are torture) and it hesitates once the engine is brought up to temperature. It also seems to have trouble idling. Once I get everything straightened out, it may make more power.

 

Also, my compression was bumped up to 12:1.

 

We went through several engine cobo's with one customers car, and the first being the LT4 package on a stock motor, it made 340rwhp with no tunning, be blew the motor up the next week when the fuel pump died and he dotonated it to death. The second was a 383 LT4 which made 400rwhp. Then a procharger 383 with fully ported lt4 heads made over 500rwhp

 

Has anybody made a comparison of the hot cam lt4 with the comp XE269HR? It looks like a similar cam with faster ramp profiles...I was thinking of using it in my next motor.