I got '99 4.8L, EC, 4x4, auto. That was very underpowered as a daily driver. So I had Jesse tune the ECM, put on a full Mangaflow, modded the stock air box, and put LS1 fans on it. It is a totally different truck. But what next? I was thinkin an 02 ECM with bigger injectors (expensive though). How about an offroad Y pipe, then have the rear O2's and EGR tuned out and lose that junk also? Don't need to go to something major like a blower or turbo, this is just a driver/work truck.

 

long tubes..

 

pacesetter LTs and ORY will be a nice power increase

id go ahead get rid of the egr and rear o2s

maybe a cam after that

 

You shouldn't need bigger injectors yet. I would either go with longtubes or a converter. One of these will probably be my next mod.

 

i just now thought about this but a set of 4.10 gears/LSD would make a noticeable differnece as well

 

02 Computer was one of the best things ive done to my truck.. definetely get around to doing that.. Of course there is a thread somewhere around here where Yelo had good luck Tuning a 99.. I however did not

 

It got 4:10's from the factory with a locking rear. My tune came out good. But I have read that the 99's had small injectors, and if you go to the 02 ECM you need the larger injectors. Yea, I think LT's are next with ORY, then have rear o2s and egr tuned out--but here is where I'm stuck--tune my '99 ecm or just get a tuned 02 (which also means 02 injectors)?

 

I've heard most everyone goes with the 02 computer upgrade. I didn't know that meant changing the injectors, but i'm pretty sure it would be worth it. I don't know from experience, but maybe some others will chime in that have done it.

 

I didnt change my injectors.. it was tuned for 99 injectors...