FoxProDenali's 2007 Sierra - Build, Show, Tell

Here's a rundown on the front.

Hard to see from the first pic above, but the previous owner had a Westin deer smasher guard on it which meant the geniuses that installed it cut holes in the factory grill.



The first thing I did was take that thing off and sell it on CL. Then used the funds to buy the black one as seen ($72 on Amazon after months of patience).

Then I wrapped the upper trim piece and lower grill in Vvivid vinyl to color match.

There was also a nice rust spot on the driver's front edge of the hood, which I ground down, repainted and then covered with an AVS Aeroskin to hide it.

The original GMC badge was toast after 10 years and the "M" actually fell out one day, so I bought a new one and painted it as well as the tow hooks. Turns out a $3 can of "Burgundy" Rustoleum was about as close to "GMC red" as I could find.

Headlights are Recon with Beamtech LED's. Forgot what the floods are; just some cheap $20 plug n plays you can find on Amazon. It's mainly for the "cool factor" as I rarely drive at night

If you've been on the fence about using a silicone-based paint sealant, then this is a visual for you.

This is rainfall on a fresh coat of Wolfgang 3.0. No, it's not "hydrophopic" in the sense that nothing will ever stick to it - like water, dirt, snow, etc - but it really does last a long time. I'm anal and wax over it, but it really is worth the investment.

But what about the intake? Surely that beast sucks the coldest of the cold air and has been properly modified to do so? The only thing it's missing is a fan!!! :lol:

I bought some cheap parts from the hardware store, eBay and Amazon as well as a used air box and went to town.

I really hated the old plastic monster manifold, plus without a catch can it was getting blasted with oil mist and collecting in the low points and pods. Screw that thing.



There are two 4" 90* elbows that fit together and source air from behind the headlight. The fender hole is sealed off because the truck didn't like it open (made a weird clicking noise on accel).

To do that, I had to remove the tray the air box sits on and bolt it directly to the truck. It actually fits that cut out perfectly. Go figure.



I just replaced the factory PCV breather with 3/8" tubing and plugged it in after the MAF.

No it didn't give me any more power.
No it's not louder.
No I didn't gain any MPG's.

That is all.

On to the exhaust.

The truck already had a Corsa "Performance" (PN 14515) cat back on it, so all I needed was headers.

I was pretty set on buying a cheap set of Speed Engineering for $300 but the buyer was a flake and it never went down.

Then a month or so ago another member put his Kooks set from his 2012 Silverado up so I jumped on it. The price was good but it was the wrong Y-pipe for my truck, so I had a local muffler shop mate it up to the Corsa.

Here's a before (stock Y on the right) and after with the Kooks. I reused the stock end of the Y, obviously.





The fit and finish is fabulous on the headers. They slid right in with no clearance issues other than the power run from the battery to the starter on the passengers side. That had to be re-wrapped with foil tape and moved over a bit. Also the second 02 sensor on that side was a bit short but that just involves messing with the anchor on the frame a bit.

The Y-pipe did find it's final resting spot on the top of the tranny crossmember but I solved that with a couple shorter hangers and now it's clear by a good 3/8".

All clear on the driver's side. Lots of mess to work around to get to get the bolts torqued down but no steering column issues or drive shaft.


The only time I'd say the truck is too loud is on a cold start and it's early in the AM. No, it's not an annoying "wake the neighbors" type of cackle, but it's aggressive. After that, it's pretty much like stock.

The first thing I noticed is how easy the truck cruised on the hwy. Quiet and effortless, almost like the wind was pushing me from behind. Since winter broke, I've been getting about 13 MPG in the city. In the first week with the Kooks, I averaged 14.8 MPG. Really unexpected and very welcomed improvement.

The second thing, of course, is the sound. Mother of god, when I come out of the end of a cloverleaf to merge on the hwy and kick it down into 3rd, the growl and the push back into the seat now is just silly. Once the tachometer hits about 2.5K it goes straight to 5k in a HURRY. This isn't burying the pedal, either...it's just really opening it up. I haven't even ran it WOT yet. With just the Corsa, you get a little extra rip and kind of a sophomoric fart of an exhaust sound which is barely louder than the engine. With the Kooks, it's almost stock car. I've given a couple buddies rides and they both said the same thing, "dude did you put a NASCAR engine in this bitch?!"

Obligatory cold start video....

Detailing is dumb.

Aren't they purdy?

No I did not put that last screw in on the pass side coil pack next to the firewall. And you can't make me!!!

After 2 years of screwing around and chasing the boogyman I finally have found a resolution of my tuning (or lack thereof) issue.

The ECU is ****ED!

I took my truck to the GM dealer to have them reflash/reset and/or update the system to see if my handheld would finally be able to communicate with the computer.

The tech tried 7 times to calibrate it and it failed each time. He then spent the next 2 hours on the phone with GM to work through the specific error codes he was getting. Still nothing.

GM determined the ECU had "been written to too many times" and would need to be replaced so he could start over fresh. The dealer's estimate is $530 for the new unit and the 1.5 hours of calibration.

All this on a truck that runs and performs as it should with no DTCs to speak of. It's like being married to and divorced from ultimate performance at the same time. :evil:

Guess I'm shopping for a new ECU....