I have a 99 silverado 1500 z71 with the 5.3 and i can not decide between the two. Does anybody know which one is better, or if there is a different company that is better.

 

neither. get a custom tune. their the same price, lifetime updates and you get more power out of it. i used nelson performance and recomend allen nelson 100%. theres others, just run a search and pick your poison.

oh, and consider swapping out to a pcm from an 02 silverado. 99's have false knock issues that the new computer will correct. nelson performance can hook you up with that too

 

I agree,
get a custom tune on a load bearing dyno or a Mail order tune like Nelson's. I went from Hypertech to custom tune and never look back, major improvement in drivability and power!

 

 

I am not sure about the false knock, but the 02 pcm are cheaper than the 99.

 

If you are dead set on a hand held get a Diablo. I have had a HPIII and Diablo and the Diablo if far superior. I went with a custom wait4me tune after I learned that $158 is cheaper than $400 for a handheld!!!!!!!!!!!!!!!!!! IMO!!!!!!!!!!!

 

Get u a custum tune, you won't regret it.

 

custom tune without a doubt but if you want a handheld i will second the motion for a diablo predator. it's a good unit till you get crazy with mods

 

man **** a hypertech, i had one till it screwed my comp up and threw all kinds of codes. a buddy of mine had one on a 02 silverado and it fried his comp. it is definately not worth the hassle. then if something happens to the programmer itself your prety much screwed. my mailorder tune is on its way