Howzit, For those of you who have a 4.3 Vortec and are looking for some cheap or free power, I'll share what I've trialed with. I have a 4.3 in my sierra and it was pretty sluggish when I got her, especially going form a V8. So here's where I started: - First was exhaust. Now you can go on craigslist or to your local junk yard and see if anyone is selling any after market dual systems and muffler. I decided to go cat back with a custom system that cost me 400 big ones. Ouch. If you shop around on a budget, you can find pretty much everything you need for a cat-back system for pretty cheap. It will add some power and make your ride sound a bit better. It still will sound like a V6 when you mash it, but it's better than stock. If you got the money, you can go with a full exhaust system with JBA headers, high flow cat, and your choice of after market mufflers and pipping. - Next I descreened the MAF sensor. Just remove the intake plumbing from both sides of the MAF carefully, remove the 4 outer torx head screws from the MAF assembly, pull off the side that has the honey comb, set the rest of the assembly carefully to the side. Now take the honey comb piece and firmly press around the edges of it. It will make a crackling sound as it separates from the rest of the housing. Toss that honey comb piece in the trash, reassemble the MAF, and put back into place. You will notice a slight difference in acceleration with all the extra air flow and best of all, Better MPG. Just with a tune up, dual exhaust and descreening the MAF, I noticed a huge improvement in my MPG. So don't waste money on those expensive ones when you can do it for free. - There is a baffle on the throttle blade inside the throttle body. Remove the air intake off the top of the throttle body. You will be able to see the throttle blade inside. If you open it, you can see the baffle on the bottom front of the blade. Take a torx bit screw driver and remove the 2 screws that hold the blade in place and remove the blade carefully. Take a dremel tool and cut that sucker off so that the blade looks like a normal blade, or a coin. Be sure not to mar any edges of the blade, or it will mess it up. Reinstall the blade and intake. Now you should notice even more difference in some throttle response. - Install some iridium spark plugs. These actually do have more efficient sparks which provides some power, better emissions, and better MPG. UPDATE: Just replaced the iridiums with regular ACDelco Platinums. The iridium were causing to harsh of a detonation therefore in cold weather and start up, they were making the engine hesitate. When I pulled them, they were also coated with charred soot. To powerful of a plug. The platinums work more efficiently with a smoother mild ride. The truck is a lot quieter as well and not as jarring on throttle response. These 4 things above that I described actually work with boosting your MPG. I tried it and it helped a lot. Throttle response was much better as well. Throttle response should be the first thing to improve before trying to improve horse power on these engines as well as any. The next things below I will mention gave me more power and quicker acceleration but totally bombed my MPG. - Cold air intakes can be expensive as hell. You can actually go to home depot and get all the pieces for really cheap, except for the cone filter. So if you can, do that. Or you can do what I did which is find insys-usa on ebay, and they sell the cold air intake for the 4.3 for only $65. It's well worth it. especially after all the other ones are like a couple hundred. You will notice an increase in response, BUT, your MPG will go down, depending what element you live in. If you live in cold climate, your MPG is even at greater risk since even more mass of cold air is moving through the intake. The reason being is because there is a intake air temperature sensor (IAT) before the MAF. The IAT gathers info of the air temp and sends it to the ECU. The ECU then figures out how much fuel to deliver and spark timing so it can efficiently run in any temperature. So when cold air hits the IAT, that's alot of dense air going into the intake. A huge mass of dense air mixed with a lean mixture of fuel = bad detonation in the cylinder. So the computer sends more fuel to each cylinder when the air is super cold. Thus dropping your fuel gauge. So I would wait to put on a cold air intake until the warmer days of the year. But if you live in hot climates, feel free to put it on and leave it on all year round. It does help pretty significant with power. - Power adders and stupid resistors on ebay. Ok, stay away from those scams. Those guys sell people a 20 cent resistor, tape it to a piece of paper, or put it in a pretty box, and charge you like $15-even $89 I've seen. Don't fall for it. If you want to give it a shot and know what it's all about, I'll explain how to do it and what it does. As I explained in the last paragraph, the IAT reads the air temp and sends that info to the ECU which in turn adjust fuel and timing accordingly. So, these "magical" resistors are actually an 4.7k ohm, 1/2 watt resistors that you can get at Radio Shack. They come in a pack a 5 for just a buck. Take one, some electrical tape, unplug the IAT cable from the sensor that's located on the intake tube before the MAF, bend the 2 ends, 2 times so the ends are a little thicker, then bend them so they can fit into the 2 holes in the plug. Tape it together so it doesn't fall out and tape it to something secure. Ok, what that does is in a nut shell, it makes the ECU read that the air coming in is 52*. As explained before, cold air means more fuel in the cylinder. If you just unplug the IAT, your CEL comes on and that's never cool. The resistor MAY add maybe just a little power, but I highly doubt it. I suggest don't try it with a cold air intake. Try it with the stock induction only. But please don't waste your money and fall for those clowns on ebay. - Power tuned ECU. I have heard mixed comments about the hand held programmers and such. It sounds pretty good with certain ones. If anyone has tried any with a 4.3 vortec and Actually had some good results, let us know. There are other options as well which could be cheaper and more beneficial in the long run. Take your vehicle to a shop that actually does tuning in house with tuning software. Or there are the three companies who most of us come to love such as, Wheatley, Blackbear, and Wait4me. Those guys will bring out the very best in your vehicle, 4.3 or not. The price is a hell of a lot cheaper as well, going dollar for horsepower. - Throttle body spacers seemed to be all the rage for awhile, then nothing. I purchased one, but have yet to put it on. I have been hearing mixed reviews about them. I was told that if you have a carb or TBI, that a spacer is more beneficial because the fuel follows the air into the intake therefore creating a bigger combustion. Has anyone actually tried a spacer on a newer vortec? If so please let us know the consensus. I hope this stuff has helped you guys a bit with your 4.3 vortec. These tips you can also use on pretty much any other engine, but I know how much the 4.3 guy's want just a little more kick out of their machines. If anyone had anything to add as well that will help us all out, please feel free. I hope this works out for you and if you guy's have a questions, just ask. Mahalo.