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Good thought but i did that already around 55,000 miles. It for sure sounds like something electricial? At least i think so?

On my wifes 2004 Yukon Denali about two months ago i was coming home from a trip and all the sudden like someone flipped a switch, there was a weird noise that appeared? Its like a low pitch hollowing sound? Very hard to discribe? I'm thinking maybe a ground came loose or something on that track? Has anyone had this happen to them? Where are all the ground locations at and how many? Thanks for any feedback. Its really driving me nuts!

PM sent! Thank you

I'll take the whole system. What tips are on it? I understand 100%!

Let me know if you have interest in sell the muffler or the whole system? Think of what you need out of it and if you want I can pick it up next week? Don't mean to pressure you just a thought? Thank you.

Where about are you in Michigan? I'm heading to Ann Arbor next week.

Looks like a piece of art work! Very nice! I would be under that truck everynight looking at that pipe! Love the x-pipe too! What did you do with the Corsa? Let me know if you want to sell the muffler?

I have been trying to find out for the last two years and I could never get a straight or correct answer! That was stated so well and makes complete sense! Thank you for that infomation! I heard the factory fans and they are so nice and quite, thats why i went with the oem fans and they look complete factory like i never did anything. I will do some more homework and get things dialed in to be right. I also have a set of 05 e-fans for my 2003 1500 hd with the 6.0 and i'm trying to get a new harness done for that and fix the problem with the harness on the 04 Denali. Thanks again for the great feedback! I've been on many other truck forumsand have gotten no where on this topic! Great Forum!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I had put a set of the oem 05 e-fans on my wifes 04 Denali a few years ago now. I was wondering who has done the same fans and what harness everyone is running? I had a company around me make a harness with better relays then other harnesses out there. The only problem is that when the ac kicks on these fans are screaming some crazy rpms and are very loud! When they both come on low speed from the pcm they sound like the high speed from the factory set on high. I have heard an 06 and you can hardly hear them on high. Does anyone make a good reliable harness that is more geared and set up like the oem set up? Just something I want to redo and be like the oem set up! Thank you for your input. Hope I can find something that works!

Man great info! Very good stuff! Thanks for your reply.

I changed that about three months back. What about O2's? I will see how it goes in the next week with the 89 tune back in? Thanks for the input guys.

All the sudden have a huge lose of mpg? I have a 2003 1500 HD with the LQ4 6.0. I always average 13.5 around town driving and could get 18 on the highway. That was with a 89 tune. I put in a 93 tune and bam the mpg went 4-5 mpg lower? I can not see it being cause by a tune? I don't want so mention the tune name but is a very well know tuner is always does top notch work! Does anyone have any idea where to ever start? I put back the 89 tune and will run that for a few weeks to see if it is something else? Looking for some thoughts and ideas. Thank you.

I've been driving like Ms. Daisy! What does everyone else get out of a tank?

Alright I went through a tank of gas and I got 238 miles on the tank and it cam out @ 9.9mpg! Ouch! That was city/highway! I would always get 13.5/14.5 mixed driving. Any thoughts?

Thats a good thought. I did fill up and reset my trip to see what that would come out to. Hopefuly thats all it is. My wifes Denali has a 93 tune and she gets at least 15 around town and 19 on the highway at 75mph. I know the hd has the 4L80 and the 14 bolt rearend which will take a hit on the mpg. I'll keep you all posted. Thanks for everyones thoughts!

I got anew 93 tune and now its sucking down the gas bad? Drive it the same as before and on the highway i was at 17-18 on a 90 mile round trip and now its at 12-13 on the highway? Any thoughts?

Could a new tune make the drivers information center and gauges read different? Something isn't right?

Nope LQ4. 04 was rated @325 and 05-06 they jumped to 335 because of the factory e-fans,i think?

I'm sure that this is talked about. I'm looking for some feedback on installing shorty headers. I was thinking of doing them on my 1500 HD. Nobody makes a mid-pipe section to make the long tube headers work and the shops around here don't want to mess with it because of the cats. So I'm on the fence on what to do? I'm thinking of the shorties and looking for your thoughts on what is the better brands out there and if anyone can give feedback for sound and performance? Looking for some good feedback. Thanks everybody!

Would like to know why the ratings are so different? Who knows?

The 04 Denali made 325 hp stock then 05-06 they added e-fans and rated them @335. My 03 1500 HD is rated @ 300hp stock (LQ4) don't know why? Mabe the 4L80 robs that much HP? Who knows?

My wife drives a 2004 Yukon Denali and I took it to the track and it ran a 14.6 around 94mph. I have Wheatley's 93 tune with a cold air, Corsa Sport, and 05 E-fans. I also have 07-present Factory 20" wheels. Just wondering what kinda of power you all think that 6.0 LQ4 is making? I think the truck weighs around 5600 plus me @ 170. Any thoughts? The truck feels very quick for a big rig! Funny stuff!

New to this forum, but have a question? Just wanted to see if i was welcome even if i don't have a SS? I have a 2004 Yukon Denali that runs 14.6's and i have a 2003 1500 HD Silverado all blacked out which the SS's inspired me to do. I have been on this forum a lot and it seems like the best one out there and i feel my trucks relate well with the SS's being a 6.0. Looking for imput from all of you. Thanks you!