BuyAmericanIron

Guess I am an old hot rod guy. Got to have headers on my vehicles.

5RWill, my truck has AR Headers with cats running the OE exhaust. It is quiet when cruising and has a nice growl when starting and accelerating. The headers took it from electric motor quiet to sounding like a sport truck. I tried both a Magnaflow and Corsa exhaust systems with headers and went back to the OE exhaust. I did have the flapper valve removed due to the substantial exhaust restriction it causes, even when open. With headers, the Magnaflow volume was too high for my taste and didn't care for the tone. The Corsa was just plain too damn loud. It was loud with manifolds and OE cats, but with headers the volume was about three times higher. I knew from the first start up that it was not going to work. Yes, those were both expensive lessons. My truck also has an MIT, ported throttle body and BlackBear tune. I really enjoy how it sounds. For me, it is a great combination. I know there is some HP loss with OE exhaust. At WOT (which my truck rarely sees) it has 5 lbs of backpressure which should equate to about 6 ~ 10 HP. Don't like it, but I can deal with it to have the sound both my wife and I like. Correction, she can live with it, I like it. Did I notice any MPG gain? No, don't think so. On a nice road trip with the cruise set at 75 mph, I can get as high as 19.8 mpg. Driving 10 miles to work with some city driving it usually gets 15 ~ 17 mpg. I don't drive like an old lady, but not like a teenager either. Just moderate/aggressive.

JWAD, here are my thoughts. Choose your tuner carefully. Without question on this forum, BlackBear is the most popular. After problems with another tuner, I spent the money and bought an Autocal and later a BlackBear tune. I highly recommend them. Excellent work. Engine and Transmission performance is substantially improved over OE. Yes, I would delete V4 mode. It caused my transmission to shift erratically and clunk at low speeds. Saw no difference in fuel economy running as a V8 all the time. Can't speak for the others, but I am on my fourth set of AR Headers. Have never had a leak, rattle or blown gasket. They are top quality and 100% Made in America. Plus, they have great resale value when it is time for a new vehicle. There is always a buyer looking for high quality used headers. Good luck with your choice.

Been watching this topic for a while and decided to comment. I had my 2016 Sierra Denali 6.2 tuned by another tuner who will not be named. He had done my 2008 Sierra Denali 6.2 and my 2010 C6 Corvette. I feel like he did a good job with both tunes. He assured me the new 8 speed transmission would be no problem. After six weeks, much frustration, numerous phone calls and a transmission that was much worse than OE (yes it is possible), I went back to the factory tune. Fast Forward a couple of weeks. I found a used Blackbear Autocal listed on this website for sale and purchased it. Contacted Blackbear, submitted payment and sent in my OE tune. A few days later, received the initial tune. Drove a few days and submitted a data log for review. A few days later had a new tune. Drove it as directed and submitted a data log for review and got a message back from Jarrad I was good to go. From initial contact to completed tune was about two ~ three weeks and several of those days were my not having time to work on it. Blackbear did a great job and I am very pleased with the outcome. Like so many others, I would highly recommend this company and their services. Rating: Engine 10/10, Transmission 9/10.

The rear diff cover gasket is reusable. It is a rubber coated steel gasket. There is no drain on the rear. No RTV needed on these trucks. The front diff has a drain plug. I found what looked like white assembly grease inside the fill plug on the front diff and the oil had a white tint to it. Looked like water contamination, but I am certain it was the grease. The transfer case has a simple drain and fill plug. Very easy. Like a few others, I refilled front and rear with Amsoil Severe Gear and the transfer case with Dex VI. A lot of people never change these fluids and don't have any problems, but it gives me piece of mind considering the cost of the investment.

1994Vmax is right. 5.3 and 6.2 use different diameter pipes. Cat back is not the same. Might have the same mounting points, but different exhaust. The headers are the same but the Y pipe is different. If you do what 1994Vmax said and order the 6.2 Y pipe with your headers and pick up the 6.2L exhaust locally, you will have a higher flowing exhaust which should be a good match for headers. That is what I would do. If you choose to go the other way, yes, the ball connector on the 5.3L is smaller than on the 6.2L. Factory exhaust will not fit unless you have a new connector welded onto your exhaust.

Victory14red, that is a very interesting article and I have read it before. Great information and very relevant to this discussion. Here is something I thought about today to add. I own a 2010 Corvette with bi-mode exhaust. For those not familiar, the bi-mode has four exhaust pipes out the back, two on each muffler. One of the pipes has what looks like a throttle plate inside. When it is open, you have virtually a straight pipe from the engine to the tip of the tailpipe. When it is closed, the exhaust gases are forced to pass through the baffles of the muffler and exit out the other pipe on the muffler. In that series of Corvette, GM rated the HP at 430 with standard mufflers and 436 with bi-mode mufflers. Now this is just a guess, but if the standard exhaust has a comparable (to this discussion) 5 psi of back pressure and the bi-mode has near zero psi back pressure, it is good for six HP on a stock engine. I would have to again guess that if you install add on's like Jon A discussed above which improve volumetric efficiency and create additional air flow through the engine there would be a bigger effect.

Agreed that even with the flapper bolted open, there is still a large piece of metal interrupting the exhaust flow. Another interesting point is the OE 6.2L exhaust. The pipe from Y pipe to muffler is 3 1/2 inch, pinched down to 3 inch right at the muffler inlet, 3 inch coming out of the muffler and through the flapper and then the tailpipe is 3 1/2 inch again to the resonator and then 3 inch from resonator to tip. Why the hell do they feed 3 1/2 inch pipe into a 3 inch muffler? It has to be for sound attenuation because in stock form it sounded like an electric car. Almost no exhaust sound at all. Now with catted AR Headers it has quite a bark through the stock exhaust and it sounds aggressive when accelerating and quiet when cruising. Kind of sounds like a big block with flowmasters. Most of my friends like the sound. I like it but hate the back pressure. Not sure how to make it better and keep it quiet. 07Softail, to answer your question, I purchased the back pressure gauge about 15 years ago from Snap On. It is a 10 lb gauge with an O2 sensor bung and a piece of high temp stainless covered flexible hose. All goes together with 1/8 inch pipe threads. Don't know if you can rent from auto parts store but I doubt it.

Tried something today out of curiosity. Pulled a rear O2 sensor and installed an exhaust back pressure gauge for testing. Truck is a 2016 Sierra Denali 6.2L. Here are the findings: Stock exhaust 30 mph cruising, .50 ~ .80 psi back pressure 55 mph cruising, .50 ~ .80 psi back pressure WOT in 3rd gear right before shifting at 5500 rpm, 5.5 ~ 5.8 psi back pressure Stock exhaust with flapper bolted open 30 mph cruising, 0 psi 55 mph cruising, 0 psi WOT in 3rd gear right before shifting at 5500 rpm, 4.8 ~ 5.1 psi back pressure Magnaflow 15318 cat back exhaust 30 mph cruising, 0 psi 55 mph cruising, 0 psi WOT in 3rd gear right before shifting at 5500 rpm, 0 ~ .1 psi back pressure. (the needle was fluctuating a bit but barely moving off of zero) I thought this was very interesting and wanted to pass on what was learned. Now the questions. How much HP do you lose with 5.5 psi back pressure? How much fuel economy does .5 to 1.0 psi cost? When accelerating with the stock exhaust at WOT, the pressure would pretty much follow the tach. I.E. 3000 rpm, 3 psi, 4000 rpm, 4 psi, 5000 rpm 5 psi. It may have been in my head, but the engine seemed to run more freely with the Magnaflow and zero back pressure at any RPM.

GooseCreek, here are my answers to your questions. 1. Good question. In most cases, I think you will be OK. The AMP boards do require periodic cleaning and lube on the pivot points, which should be no issue for a farmer. 2. Another good question. AMP boards are well designed and very durable. With that said, I am not sure you can bury your truck up to the frame and no cause damage to the boards or the drive motors. Though they are in no way fragile, I doubt they were designed to take that kind of abuse. 3. Another good question. AMP boards tuck up tight (within about 1/4 on an inch) to the bottom of the rocker panels. If you bottom out your frame and rocker panels in the rocks or similar conditions, you will most likely cause severe and non-repairable damage to the boards. 4. Probably not, but possibly. The motors and electrical connections are designed to be waterproof. They are mounted under your truck and see considerable water and snow spray (in the northern climate). A low water splash or dip will not hurt them. If you bury your truck in a creek crossing and the boards are under water for a couple of days before you are pulled out, that may be another story. In this case, you are going to have numerous other issues anyway and the boards will be the least of your concerns. 5. Yes, the AMP boards do provide pretty good protection to the rocker panels from stone damage. AMP boards will help with the sliding on the edge of your seat. For me and my family members, they are just the right height to help with ingress and egress. I can put my left leg out onto the board and easily step out of the truck without sliding on the edge of the seat at all. Same with getting in. Yes they are very well designed, but like everything else, they have a limit to the abuse they can withstand.

I spoke to Anthony at MVI. He said the BCM can be re-programmed, but it is difficult, expensive and requires dealer involvement which can bring it's own set of problems. He said if you are close to him and bring it to his shop it is not a problem. In the end, he strongly recommends against trying to re-program the BCM. Just go with one of the diode mods in this forum and consider it done. I did the 10/22 and it works just fine for my application.

Unrelated and almost certainly a separate issue.

Tong Lu, I did some research and was unable to find the low beam relay. Ended up doing the 10/22 mod which ties fog lights into the parking lamp circuit. On the 2016, if you turn on fog lights, it disables Intellibeam which is a very nice feature. Only possible issue is that you have fogs on at all lighting positions, Auto, Parking lights, All lights (low and high beam). Can't remember the last time I used parking lights only, so don't see it as being an issue. For you guys having difficulty inserting the diode into the plug, try using a large sewing pin and sliding it at an angle into the corner of the connector at the selected wire position. This will push it to the opposite side and make room for the diode. Also, try cutting the end of the diode wire at a sharp angle with a pair of clippers. This will make a sharp point and help with installation into the back of the plug. Remember, you are trying to slide the diode along side the existing wire. Pushing it into a corner is your best bet. It should insert about half an inch when you find the right spot.

Got to agree with GMC-AT. I don't foresee any headlight/fog light updates on my truck. Lights are impressive!

Are you saying TRS makes a replacement fog light for the 2016 GMC Sierra? If so, do you have a link?