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Performance Mods!

04AvGuy

New Member
Joined
Jun 24, 2016
Messages
8
Location
Phoenix
So I have a stock 2004 Avalanche 1500 with 156,000 miles and I am looking for help deciding what performance mods to do.  I want acceleration not top speed and I also want a good sound.  I do not want the stock 4 wheel drive capabilities to be limited by these mods because I go 4 wheeling around twice a month but nothing crazy.  My budget is around $3,000.  I have looked at the other posts and people seem to think that an intake, exhaust, and tune are a good way to go.  I am thinking of getting Doug Thorley Tri-Y headers, a Comp Cam (I dont know which cam is best for what I want), Stage 1 CNC ported heads from Total Engine Airflow, and Yukon Gears (either 4.56 or 4.8:cool:.  I am going to be doing all the work myself with the help of some friends.  I also am fairly new to the performance world but I want to learn.  I plan on running either open headers or running true dual strait pipes out the rear (possibly with glass packs).  I would like to know if a tuner is worth the money and if anyone thinks there is a way to get better horsepower and torque gains for the same amount of money. Also, what is going to break first on a modded avalanche I'm thinking maybe the trans (i have the crappy 4l60e), rear end, ring and pinion, u joints, and possibly the yoke???  I am open to any suggestions.  Any help is greatly appreciated.
 
First welcome to the site!
I agree with many things you are looking at as far as increasing torque and not concentrating on H.P. too many people get caught up in some H.P. chase and forget that the Av is a 6,000 lb. truck with the aerodynamics of a brick so obtaining some high rpm high speed figure can get expensive to reach. One caution is loud sound doesn't equal torque or h.p. so don't trick yourself with loud intakes and exhaust and think you found power....Many have said on this site that the stock air intake actually draws in enough air unless you go to forced induction or some heavy modified cam. It also doesn't really improve gas mileage either but many owners want to justify the expense with short term claims of more power or MPG. (I am one with a CAI and would not waste money on one again unless I did one of the mods mentioned.)
I do believe in a good CAT back exhaust system to open up the exhaust flow and I would not try to reinvent the wheel on that mod. I went with a Corsa Sport system on my 2004 and also on my 2008 AVs.
I went with them because of the ease of install and the lifetime warranty as well as improving performance. It is an expense setup though but you never have to buy another exhaust.
http://www.corsaperformance.com/viewpart.aspx?year=2004&make=Chevrolet&model=Avalanche&partnum=14250&cfg=282

I also try not to tear into a good working motor so uless you are having oil use issues or some other problem I would save up my money and use a bolt on setup for increasing torque such as a magnusson supercharger. Again it is an expensive project but well worth the expense in that it gives you more usable torque when you need it for off-road or towing etc. It also has a 3 year warranty on drivetrain issues I believe.
http://www.magnusonproducts.com/p-67-chevrolet-gmc-suv-48l-53l-60l-2004-2006-radix-retro-magnuson-supercharger.aspx

Good luck with your decisions.
 
Thanks for the quick response!  I have looked at cat back exhausts and they are kind of expensive and I don't know if they will give me as much power as headers will.  The reason for straight pipes is because they are really cheap to make, they aren't very restrictive (I am unsure if the lack of back pressure will be a problem though), and I love the sound.  I will look into the supercharger also, it is expensive but it looks like it might be the best option.
 
The way I look at mods is to look at the whole picture and try to find an already tested and approved setup. If you try to Frankenstein together a collection of parts you then become the "test dummy" and what may be the best part may not work well with other parts in your setup. I also think that if you beef up one part of your drive-train you will find out that there are other week spots such as your transmission and they may fail so if you get too extreme you may find out it becomes a never ending battle to keep the AV on the road. It's like the old saying "how much performance depends on what you can afford in time,parts and money."
 
You've slightly under budgeted for the parts you've listed plus other parts you will need:

Heads  $1400
Headers  700
Cam        400
Gears      550
Pushrods  100
Headbolts 100
Misc        100

Total $3350

Once you've torn into it you should probably also consider replacing the cam timing set and possibly the oil pump.  That's probably another $300.

Unless you choose a mild cam (and I certainly wouldn't bother with doing the heads if doing a mild cam) you are going to need a custom tune.  That's another $150-$500.

Once again assuming you don't choose a mild cam, you should be looking at a looser torque converter and aux tranny cooler.  I'm happy with my Circle D 3200 stall converter at around $400.  An inexpensive tranny cooler, fittings, etc. is probably another $100, but since you are doing some presumably slow-speed off-roading you should probably get one with a fan, so figure another $100 or so.

I'd say realistically with what you mentioned doing you should be thinking more budget-wise around $5000.

If you don't want to spend that much money then I'd ditch the heads, choose a cam that wouldn't require as high a stall speed converter, go with a stock 6-cylinder Trailblazer converter for under $200 that will get you a few hundred more rpm stall speed, and an aux tranny cooler without a fan.  That knocks nearly $2000 off what you are looking at.
 
I take it smog laws are not a factor where you live? Have to keep in mind your O2 sensors and cat faults throwing codes, especially if you completely gut the factory exhaust and run long tube headers as I did. Cat back kits really save you the headaches.
 
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