what are the best mods for a '99

[phastmuvr]

I have a 4x4 1999 Tahoe, pretty much all stock with the exception of a K&N filter and a flowmaster.

Do those hypertech programmers actually make a difference? What else can I do to get some more HP and torque?

[andjh123]

Ok here's my take on this subject--sorry for the length.

First, all those small things (exhaust, chip/programmer, free-flow filter, cold air intake, the "tornado" etc..) all make a little difference. All of them combined (I know b/c I bought all of these things for an old '95 I owned at one point) make just a barely noticeable difference in performance. The kind of money it takes to get a real hop up in performance (engine/transmission mods.), or even the money spent on all these little mods, is alot better spent on doing stuff to make your tahoe look better (interior, exterior, sound system etc.)

The good old tahoe wasn't built for speed, and when people see it they are alot more concerned (and impressed) by how it looks rather than if it can do the 1/4 mile in 20 seconds as opposed to 40. If it's off-roading your interested in, stock chevy's get plenty of power and it should be giant tires you're concerned with. Now a good sounding exhaust note is the exception here, but seriously, put some nice wheels/tires on there, lift it up or lower it down (whatever your preference), fender flares, brush guard, sound system etc. etc...

The 1998 I have now has alot of the above mentioned features on it and no engine performance modifications aside from a straight pipe exhaust and the K&N. I have received many more compliments and offers to buy this vehicle than I ever did with the old '95.

[phastmuvr]

I'm not concerned about speed really. I use the vehicle as a daily driver and as a tow vehicle. It would just be nice to get up those steep hills a little faster while towing.

[bartlanz]

Transplant a deisel engine and tranny into it but as andjh123 said, Make it look pretty! Where you say you do alot of towing with it, I might recomend doing and upgrade to the breaks. i think im about to do my second rotor change in 2 months

[andjh123]

In that case, I'd say go with the programmer and stay away from those pre-programmed "chips." I've heard some bad stories about those chips not being configured correctly and shorting out parts of your electrical and computer system. You could look into some nice ignition system/spark plug combos available that are supposed to add some decent power for a fairly reasonable price. And if you've got the means and the time to install yourself, headers are definitely a big bang for the buck--paying someone else to put them on can get a little expensive (in my opinion, of course).

[forp00]

This is kind of a long post, but I have done a few different things and I want to go through them all.

I have a 99 2-door 4wd LT and have made the following mods:
Hypertech power programmer $350
160 degree stat $50 - $70
Gibson headers $400
Flowmaster 70 series muffler $350 with custom pipes
K&N cold air intake $250


For Looks I have chrome nerf bars and Scorpio Weld wheels and Pirelli Scorpion ST tyers


First the hypertech
Being a tech person I love being able to interface with my computer. You can advance the spark with the Power tuning option which requires 91 octane.
I like this. I tried removing the programming last month and had to put it back on. When you punch it with out the programming the truck kind of bogs down a bit (my truck any way) and with the good gas and the spark advance it gets right on it.

Next you can optimize for the 160 degree stat
This is good, love the fact that my truck runs cooler. Not that good in the winter though. Windshield wont defrost as well.

Shift firmness
Again this is a noticeable difference where the clutch lets out quicker and firmer. I would imagine that this would reduce ware on the clutch.

Higher RPMs
I have this setting engaged but don't think that much of it.

The other features let you change the tier size and adjust for different gears.

It also lets you raise your top speed to 126 MPH (I think)

So all in all I really like my programmer.


The headers did not make a huge difference, though they do look cool. They did bolt right on pretty easy. It did make one of the spark plugs hard to get at. I still have the stock down pipe which may be restricting the air flow. Maybe that’s why.

The K&N cold air intake did make a good difference. This really made the meaty sound come out of the engine. Also it makes this really cool hissing sound when you let off the gas. There was a noticeable change in performance as well. There is a loud vibration from 3000 – 3300 rpm’s that the stock intake cancels out with that big empty box thing that says Vortec on it.


The muffler did not make a noticeable difference. Again, this might be due to the fact that my stock down pipe is restricting my system (it does have a nasty bend) and any upgrade may not be realized until that is replaced. The 70 series is the quietest muffler that Flowmaster made when I bought it, and it does sound good. Again, as I said before the cold air intake made the biggest difference in sound.

So I did all the mods except the muffler. They were all pretty easy and I am glad I did them all. The headers were my only performance regret, but they do look cool, and show that you care (also weigh about 30 lbs or so less.


I did get vented and slotted front rotors and love them $190 for the pair.

I have not and probably will not ever dyno my truck but I would say that I am getting about 270 – 280 Hp and 350 – 370 Torq, I’m guessing who knows, but I can beat regular Tahoe’s off the line. Plus it sounds great.

Good luck.

[bretzg]

I did the Hypertech, K&N and a Borla exhaust on my Tahoe. I think the K&N helped a lot and sounds good. The Hypertech makes a noticeable difference and I think mine has better throttle response and I like the firmer shifts. I'm not too crazy about the Borla exhaust as mine has a really loud and annoying resonance at 1,700 - 1,900 RPM which is where the truck sits at about 70 - 75 mph and it's also there a lot in town. I'll probably look to get a quieter muffler as I like the way the Borla system looks at the tail pipe.

[gurrzt]

This is what I would do:

1. upgrade rearend gears to 4.10, Eaton Posi
2. Yank SS3800 2.7 STR Torque Converter
3. Transgo shift kit #3 washer
4. TCI SF29 flexplate
5. B&M 24K super cooler (transmission)
6. B&M 3 quart deep trans pan
7. NOS 75 wet shot.
8. Delete Torque Management, and adjust shift points (PCM)

Then go out for a drive