Here is the situation. I have a 2001 Jimmy with 4x4 and a 5 speed with 3.42 gearing. Had new tires installed today, 31,10.50, 15 Actualdimensions are just around 30 inches and under 10 wide on stock wheels. It is feeling weak on the highway in 5th and would like to gain back the response that the stock tires offered.So tommorrow i will be replacing plugs, cap, rotor,fuel filter, cleaning egr and inspecting pcv. Unit has 64000 miles. Here is the question, what would a fai, magnaflow muffler with 2.5pipes and a Jet stage oneprogramer produce ? Basically want to maximize the throttle response and torque so i can achieve stock like or improved performance and mileage with the tires? I realize that 3.73 gears would achieve this, but thought that these mods may achieve the same. Any input would be appreciated thanks.

 

CAI, free flowing exhaust, and a chip will always yeald good results. You could expect approx 20+ HP gain though the exact amount i couldnt speak to. Definately though it will be a lot more responsive with the exaust as the factory muffler is pretty restrictive.

 

<no cat and new muffler- I didnt really notice any difference in performance....

 

I added high flow cat and a new magnaflow muffler on mine and picked up more than a sec. in the 1/4 mile it is worth it!

 

Then your cat was hella clogged when you replaced it, lol.

 

According to the k&n web site, the cai with give the blazer 7.7 more hp. My personal experiance, better throttle responce and more mpg. I have a dynomax cat-back exhaust and it also increased my mpg, rpm's were much lower on the highway due to less restriction letting the engine breathe easier and it just seemed to have more go at higher speeds. I plan on getting a high flow cat from which i hear increase you mid range power a bit. Look into getting a wait4me toon. They are cheaper and seem to have much better reviews on gm-trucks.com. Just my 2 cents. Adam

 

Gonna start with a drop in K+N, next will be y pipe and exhaust. I did some digging on the wait4me ecm and that sounds likely in the future except i need to find someone to clear the code it throws after the install before i buy one. I dont quite understand how your rpms would drop from a simple exhaust replacement, gear ratiosdidnt change!

 

the engine doesnt have to work as hard tomaintain power. since the engine isnt working as hard, the RPM's go down (slightly)

 

No modification short of a gear or tire swap will alter cruising RPM with the torque converter in full lock.

 

with bigger tires you will always lose power because you have to turn bigger tires and as for cai its 7.7 at the motor which through drive train loss you will not really even notice it i put one on my 01 and didnt notice really anything just get the programmer
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