ok, my truck is a 97 dak with the sawed off 5.2 (3.9) i have a lift and am running 33s and its all it can do to pull em, the gear ratio is 3:92
so thats just about right, its just weak on 0-60 how can i get more power outta that lil demon under the hood? I have a cold air intake and a resistor chip so it can breathe.....what else can i do? headers? somebody told me to put on some 1.6 roller rockers....if i did full exhaust and some rockers along with a v8 throttle body would that help it any? If you have a hot 3.9 PLZ tell me how to make mine run(without getting 9 mpg)...........one more thing, im planning on doing away with my cat, so can i get a upstream o2 sensor and get away with it

 

high flow muffler, high flow cat, headers, computer chips..

 

the only thing that is gonna get that truck up and rolling are gears. if you keep the 33 inch tires you are gonna have to swap out the gears. no matter what you do to the motor it wont help. i had stock 3.55 in my dak and went to the 4.10. big difference and kinda pricey at 1600.00 because it is 4x4 but well worth the investment

 

3.92s to a 4:11 wouldt make much differce, im not really wanting to get ****ty gas mileage either, my camaro had 323s and i swapped to 456s, by by gas milage

 

if your " resisitor chip" is what i think it is. its doing nothing for you.

 

This is incorrect. Out of anything you could do, besides maybe a SC/Turbo setup, the 4:10 gears will be most noticable. I myself have a 5.2l, and went from 3.55's to 4:10's. I know have to becareful on take off or I will break the tires loose everytime. Its almost too much. I was planning on a lift with 35's and 4:10s, but chewed up some spider gears and needed to do some work back there anyway, so the 4:10's came early. Once I get those 35's it will even out a bit better.

If you change the gears in a car with out changing the tires size, you will see a MPG loss do to your rpm range being higher. But in this case, because of the large tire diameter it will actually be closer to stock thenyouare now.Your motor will not have to work as hard to turn the tires the same amount, thusyou might actually see an improvement in MPG.

My list of things would be as follows (in order):

1. Exhuast + CAI
2. Headers (I would do shorty headers myself, maybe even a bit of header wrap while your at it.)
3. V8 TB
4. 1.6 rockers
5. Gears (If your only 2wd, I might actually do these before the rockers myself.)

Also get rid of the resistor chip. Your motor needs a certain A/F mixture or damage can occur. As for the CAT, I have never seen any data that shows how much you gain from a hi-flow CAt or removing it altogether, soI leave that to you. It will throw a check engine light with out the O2 sensor fooler thing-a-ma-jig.