2000 Silverado Z71 5.3L auto autotrac and lowered

Getting to be time to address the exhaust. It'll be next, after I lower the truck another 2 inches. I've already decided to go single 3 inch to a 1 in 2 out muffler, then 2.25 over the axle. I need help before the muffler though.

I'm a huge fan of long tube headers, and I kinda like tri-y headers, but when it comes down to specifics I start needing a bit of advice. The ones I'm looking at are:

Doug Thorley tri-y headers
Pacesetter long tubes
Dynatech headers

Any opinions on these? I'm also open to other suggestions. I'm kinda leaning towards the Pacesetters because they have 1 3/4 inch primaries, 3 inch collectors, and a ceramic coating for a decent price. The Thorleys look like they'd be easier to install though. I had a set of Pacesetters on the S10 and they made a big difference in the truck's available power, but they were a major pain to get in. I've never run a tri-y header before, so no idea what they'll do for low end torque in real life.

imo the dougs headers. lil expensive though.. Not sure if thats the ex-wifes company or his new spin.. would look for newer company.

I had gibson shorties on my 4.8L I liked them. moved the powerband up a tad.

Dougs Headers are post divorce brand, Doug Thorley Headers are pre-divorce brand; both great brands though. I love mine on my truck and honestly dont think I would gain any power from going to long-tubes. If you have the ability I would do a true dual system with 2.5" (not 2.25") pipe. That way you'll have room for more power in the future and not choke it should you decide to add a power adder or more cubes.... at least up to 500hp. More than 500 and I'd go with a true dual 3" setup.

I'm thinking of going with a splitter that will take dual 2.5/3 inch header outlets into a single 3 inch pipe into a single muffler, with dual 2.25 outputs on it. I'm figuring that the short 3 inch section from the 2in1 to the muffler will do a good job of blending, then the dual outs will help cut the sound. Dual 2.25s will flow more than a single 3 inch.

If I do anything with the engine it'll be to move to a 4.8L. It only takes a few small mods to get the same power from a 4.8 as you get in a 5.3, and you get way better mileage to boot. As things sit now we're seeing about 16-18MPG out of the 5.3 in a reg ca 4x4, while my mother with a 4.8 is seeing 22 with an ext cab 2WD, and her truck feels a little faster than mine does. True, hers is new while mine has about 250K on the clock, but still. As soon as I work out the suspension and exhaust, then deal with the seats and center console situation, it'll be time to start putting back cash towards and engine and transmission . Last step will be the blue paint, with any luck the engine, transmission and paintwork will take place this time next year.

Ya know, for someone that moves as slowly as I normally do, I've bee proceeding at a pretty good clip on this truck.

EDIT - Writing off Doug's headers, they come in shorty version only for the 1999+ 4x4. I don't like shorties at all, and the exhaust manifolds are pretty close to shorties as they are. Thanks for the suggestion though.

Speaking as someone who had a 5.3 I wouldn't write it off that quickly. My 06 crew cab gets 16-18 around town and 20 hwy and that's a 4 door crew cab. Maybe yours just needs freshening to a newer year or tuning. When I first got this truck I had just came off a 96 Vortec 350 and I didn't like the power package at all because I was used to the low end torgue. But now that I finally realize this little 5.3 just loves to rev and makes power at a higher rpm I really have grown to like it. It seems like the longer I have it the better it runs.

I have about 85,000 miles on mine now so still a lot of life left in it, but in a few years I am thinking about trying to find the alum l33 and build a nice NA motor with it. One that has a little undercurrent of nastiness if you know what I mean.

Here are some ceramic coated Hooker Super Competition Series longtubes.

99-05 4.8,5.3,6.0

1 5/8"x 30" primaries with 3"x6" long collectors with 18 gauge tubing
$483.94 ($439 from Summit Racing)
2850HKR (painted)
http://www.holley.com/2850HKR.asp

$633.44 ($575.99 at Summit Racing)
2850-1HKR (ceramic)
http://www.holley.com/2850-1HKR.asp

Hooker 16 gauge aluminized Y-pipe specifically for the 2850HKR and 2850-1HKR Supercomp headers
$241.94 ($219.95 at Summit Racing)
p/n 16785HKR
http://www.holley.com/16785HKR.asp


1 3/4" x 30" primaries with 6" x 9" long collectors
No price on the Holley/Hooker site (Summit Racing's price is $515.95)
2851HKR (painted)
http://www.holley.com/2851HKR.asp

$775 ($704.95 at Summit Racing)
2851-1HKR (ceramic)
http://www.holley.com/2851-1HKR.asp

Hooker aluminized Y-pipe specifically for the 2851HKR and 2851-1HKR Supercomp headers
$279.34 ($253.95 from Summit Racing)
p/n 16786HKR
http://www.holley.com/16786HKR.asp

For mostly highway cruising, I would go with the 1-5/8" primaries on a 4.8 and 5.3. I would use the 1 3/4" primary headers on a highly modded 5.3 or 6.0 or any engine with a supercharger. The smaller primary tubes will help keep exhaust velocity up even at lower engine speeds. You certainly dont want to lose any off idle torque on tehse GEN 3 4.8,5.3,6.0 engines. Once the revs get up, these engines sure do make the power.

I have had my 2462-1hkr Hooker Competition (James B. used the SUPER-Competition 2806-1HKR on his SBC setup) for 8-9 years now. I have some rust on them now, but nothing that will rust through anytime soon. I used to run painted mild steel headers and the 3 years I had teh truck, I had to replace the headers every single spring because the salt that is used on the highways would rot the uncoated steel. The extra $200 for ceramic coating has paid for itself many times over.

Those Hooker Y-pipes sure are expensive, and they are just aluminized, not stainless.

I would just get a nice set of full longtube headers, and have a muffler shop fab up a Y pipe.

I would never swap out a 5.3 for a 4.8.
Here is the 2000 GEN 3 engine data.
VORTEC 4800 V8 ENGINE 270hp@5200rpm 285 lb/ft torque@4000rpm
VORTEC 5300 V8 ENGINE 285@5200rpm 325 lb./ft torque@4000rpm

Just remember that the GEN 3 engine output numbers were released BEFORE the new SAE CERTIFIED POWER&TORQUE numbers. I think it would be cool to see what the older 4.8/5.3/6.0's would actually output using this new CERTIFIED output testing.

I just looked up some GEN 4 engines, that use a cam phasing VVT(Variable Valve Timing) to get the big power numbers while still retaining decent low rpm torque.
2010 Vortec 4.8L V-8 VVT (L20) and it makes 302hp@5600rpm and 305 lb/ft@4600rpm on gasoline
2010 Vortec 5.3L V-8 VVT (LC9) and it makes 315hp@5200rpm and 335 lb/ft@4000 rpm on gasoline
326hp@5300rpm and 348 lb/ft@ 4400rpm on E85

Just looking at the 4.8l torque peak of 4600rpm, thats the POWER PEAK of the 1996-2002 Vortec 350 with 255hp@4600rpm. My the truck engines powerbands have changed a LOT over the years.

peace
Hog

Are these any good?

http://www.summitracing.com/parts/WLK-35934/

The headers I have are slip fit, and I'd like to avoid welding anything to them if possible. I would use these to attach the headers to the cats, system would be welded from then on.

I've used them. IF I had to use a clamp again, I'd definitely but those. However, IF I had a choice, I wouldn't use clamps at all. Especially for someone who is as anal as you are. Over time they'll prob leak a little bit and it will drive you crazy.

Hmmm... what would be the weld-free way to do this then? I need to be able to drop the exhaust without visiting an exhaust shop to get them hooked back up.

Speeder wrote:

Hmmm... what would be the weld-free way to do this then? I need to be able to drop the exhaust without visiting an exhaust shop to get them hooked back up.

http://www.summitracing.com/parts/FLO-15938/

Thanks. So the two bolt connection won't cause a problem? If not, I can get a set in.

nope, they work very nice and create a positive seal, i wont ever use a 3 bolt flange again.

Excellent, thanks. Ordered a couple of sets yesterday, only in the 3 inch version. Going to have the exhaust shop put them in a couple of places, one right off the headers and one at the muffler so the intermediate pipes can be removed. Got a transmission to do not long after the exhaust.

Update - After three long months, some 3 inch diameter fittings that Howard sent to me have come in. When I go to get an exhaust put on the truck, these will be used to hold it together. These things are tough too, the package looked like an elephant sat on it, but there was no damage to the fittings themselves, not even on the edges where you'd expect a drop to concrete to at least leave a dent. Unfortunately, Howard didn't have many of these fittings, and I don't know if he has any more of them. If not, then NEENER NEENER to the rest of you. Naw seriously, I've seen them on the net in the states, so if someone really wanted some they can be had.

After the trans is in, I'll be working on getting the broken bolt on the head fixed, and then the long tube headers and new mufflers go on and these fittings will be used to hold it all together.

Those look real nice. I think I would use some antiseize on them though. They look like they could be fun to undo if they become the least bit corroded.