On Friday, I had my Flowmaster 50 Series SUV installed on my '99 5.2. It has a great sound, but I honestly did not notice much difference driving around town (mostly 40 mph and under). Then, this morning on my usual drive to work, I finally noticed a change. There is a really really steep hill on my way to work, over a mile in length. Usually, I can pull about 55 mph on the hill. If I give it full throttle, my automatic usually downshifts another gear, and I might be able to get up to 58 or 59 mph, but it really struggles to accelerate at that high of RPM on that much slope.

This morning, I was doing about 55 as usual. At the steepest part of the hill, I stepped on it to see if there was any difference. It downshifted like usual, but it actully started accelerating. I was up to 65 before I knew it. Had to let off the gas to avoid running into the guy in front of me.

Honestly, I had hoped that the exhaust upgrade would help my low end more, but now that I have improved top end, I guess I'm still happy. I think the Fastman TB was the best upgrade for my low end so far.

Next upgrade, Hypertech III.

 

I had a similar experience when I went to the 7x9" K&N filter on my FIPK II kit... except the truck didnt need to downshift to accelerate over the hills (mtns really... Sierra Nevada's).

you should take some mental notes on how each upgrade affects the performance on that hill. steep hills are a good way to see how a mod benifits your truck. Your next step would be to maintain your 55 mph speed in OD... then accelerate up hill in OD...

 

I literally can't even accelerate up small hills in OD. When in OD, the only time I can accelerate is on flat ground. As soon as I hit any kind of hill, the engine bogs down, then the transmission downshifts, and I have power again. I don't have a tac, but when I am in OD, the RPM's are really really low. Most of the time, I drive around with the OD off. It's better for my trans that way, and I have more power. Only time I really use the OD is on flat sections of highway at speeds over 50. I have often wondered if I have the death flash of something. That's why my next upgrade is going to be the Hypertech III.

Another cure I thought of for this problem would be to get lower gears (go from 3.55 to 4.10). Then, when I'm in OD at highway speed, I would be at a little higher RPM, and I think I would be able to accelerate better in OD. Lower gears would also be great for my low end performance, and I could put 285's on without increases sluggishness.

 

Oh, and when I say it downshifts to be able to accelerate, I mean it has already downshifted out of OD, then it downshifts again. That is the only time I can accelerate on that steep hill (used to be only a little acceleration, but now its improved).

I think the auto is a 3sp, with 4th being OD. So when I am actually accelerating up the hill with any kind of force, I am in 2nd. In 3rd, I can maintain my speed, but very hard to accelerate any. Can't even think about accelerating in 4th (OD).

 

I have the 285's on my truck with 4.11's and it's awesome. with my truck in it's current state, there is more than enough power to go up some steeper hills w/o downshifting. I'm really happy with it and suggest all of the mods that I have for anyone who wants to upgrade thier truck.

the only thing I havent done yet to my truck is the 1.7 roller rockers... which are sitting on a shelf in the closet [sm=headbang.gif]