digitalfiend
Expert Overthinker
I've always wanted to use Doug Thorley 4-2-1 headers. Everything I've ever read about header design touts a 4-2-1 header as the best thing for a daily driver that routinely goes through stop and go city driving. This design header is supposed to be great at increasing low-RPM torque and improving MPG...oh yeah...for all of you that don't care about that, lemme put it to you like this: they help you go faster.
The biggest problem with Doug Thorley headers is that they're very proud of them. They're made of mild steel and they're ceramic coated inside and outside...but they can't usually be had for less than $590. However, if you watch jegs.com closely enough you'll see that they will occasionally go on sale for $449 shipped. I do watch jegs.com closely, so I got what I consider to be a steal on these headers.
I also picked up some stage 8 locking header bolts and a set of Percy's Seal-4-Good Header Gaskets:
*) Doug Thorley 4-2-1 Headers: http://www.jegs.com/i/Doug+Thorley/702/310Y-1-C/10002/-1
*) Header Gaskets: http://www.summitracing.com/parts/php-66032/overview/
*) Stage 8 Locking Header Bolts: http://www.summitracing.com/parts/stg-8900/overview/
WARNING: Do not believe what Doug Thorley tells you that the headers and y-pipe being a direct bolt in that requires no fabrication. For my 2004 Tahoe the y-pipe was ANYTHING but bolt-in. I even called Doug Thorley directly and directly asked them if the headers and y-pipe were a direct bolt in...they said 'yes'. I will forever wonder if they'll share any of the crack they were smoking when they came to this conclusion.
Let the fun begin:
I was removing the stock exhaust manifolds from my 2004 Tahoe. The rear bolts on BOTH sides of the manifolds (closest to the firewall) snapped without much effort on my part. The others all came out fine. Based on what I've researched it's best to plan for this to happen instead of hoping that it doesn't. So tighten up your welding skills before you pull the exhaust manifolds off your ride.
After I removed the drive side exhaust manifold I snapped a photo of it. Here's a shot of the driver side bolt snapped off well below the surface of the cylinder head:
I found it was easier for me to cut a spare bolt to be really short and then weld that on. I did the welding without removing anything from my truck...just remember to plug the other exhaust ports so that you don't get junk in them from welding. I was able to do the repair without removing the cylinder head and/or engine from my Tahoe:
Once it cools enough from the welding you need to slowly work the bolt back and forth as you advance it out. Don't sweat it if you break the bolt head off that you just welded on because you can always weld it right back on:
Once you extract the bolts you have a really cool story and a cool souvenir:
Or, in my case, two really cool souvenirs:
And yes, I did get Darth Vader to hold the bolts for me while I took a photographs.
Once I got the stock system off and the broken bolts removed I got the new headers bolted on and locked into place (thank you dear stage 8):
This is where I found out that the y-pipe that came with the kit would not fit and would not bolt up to the rest of the stock exhaust system. I quit working on this at 4:30am this morning only to get up and have the kids to school by 8:30am. I don't care what anyone says...but the best way to wake up is knowing that you get to drive a 6-speed Tahoe with OPEN HEADERS across San Antonio in the morning. While open headers is a beautiful sound the SAPD won't agree...and while I escaped any kind of citation or ticket today my luck won't hold out. So the first thing I did after I dropped the kids off at school was to go to an excellent exhaust shop:
If you live near San Antonio, TX who needs custom exhaust work then do NOT hesitate to check out Option Muffler Shop. The main guy combined the Thorley y-pip and the end of the stock y-pipe:
The y-pipe doesn't have catalytic converters. Other than that, and dealing with the fabrication to make them work, the kit is remarkable. I have only driven around town today but I keep noticing that the Tahoe has better power under 3000.
The two things to look out for are the driver-side header hitting on the body and the passenger header hitting on the heat shield that sits underneath the air conditioning equipment. I highly reccommned these headers. I'll be making a road trip this weekend and I'll post what my mileage is once that trip is over.
The biggest problem with Doug Thorley headers is that they're very proud of them. They're made of mild steel and they're ceramic coated inside and outside...but they can't usually be had for less than $590. However, if you watch jegs.com closely enough you'll see that they will occasionally go on sale for $449 shipped. I do watch jegs.com closely, so I got what I consider to be a steal on these headers.
I also picked up some stage 8 locking header bolts and a set of Percy's Seal-4-Good Header Gaskets:
*) Doug Thorley 4-2-1 Headers: http://www.jegs.com/i/Doug+Thorley/702/310Y-1-C/10002/-1
*) Header Gaskets: http://www.summitracing.com/parts/php-66032/overview/
*) Stage 8 Locking Header Bolts: http://www.summitracing.com/parts/stg-8900/overview/
WARNING: Do not believe what Doug Thorley tells you that the headers and y-pipe being a direct bolt in that requires no fabrication. For my 2004 Tahoe the y-pipe was ANYTHING but bolt-in. I even called Doug Thorley directly and directly asked them if the headers and y-pipe were a direct bolt in...they said 'yes'. I will forever wonder if they'll share any of the crack they were smoking when they came to this conclusion.
Let the fun begin:
I was removing the stock exhaust manifolds from my 2004 Tahoe. The rear bolts on BOTH sides of the manifolds (closest to the firewall) snapped without much effort on my part. The others all came out fine. Based on what I've researched it's best to plan for this to happen instead of hoping that it doesn't. So tighten up your welding skills before you pull the exhaust manifolds off your ride.
After I removed the drive side exhaust manifold I snapped a photo of it. Here's a shot of the driver side bolt snapped off well below the surface of the cylinder head:
I found it was easier for me to cut a spare bolt to be really short and then weld that on. I did the welding without removing anything from my truck...just remember to plug the other exhaust ports so that you don't get junk in them from welding. I was able to do the repair without removing the cylinder head and/or engine from my Tahoe:
Once it cools enough from the welding you need to slowly work the bolt back and forth as you advance it out. Don't sweat it if you break the bolt head off that you just welded on because you can always weld it right back on:
Once you extract the bolts you have a really cool story and a cool souvenir:
Or, in my case, two really cool souvenirs:
And yes, I did get Darth Vader to hold the bolts for me while I took a photographs.
Once I got the stock system off and the broken bolts removed I got the new headers bolted on and locked into place (thank you dear stage 8):
This is where I found out that the y-pipe that came with the kit would not fit and would not bolt up to the rest of the stock exhaust system. I quit working on this at 4:30am this morning only to get up and have the kids to school by 8:30am. I don't care what anyone says...but the best way to wake up is knowing that you get to drive a 6-speed Tahoe with OPEN HEADERS across San Antonio in the morning. While open headers is a beautiful sound the SAPD won't agree...and while I escaped any kind of citation or ticket today my luck won't hold out. So the first thing I did after I dropped the kids off at school was to go to an excellent exhaust shop:
If you live near San Antonio, TX who needs custom exhaust work then do NOT hesitate to check out Option Muffler Shop. The main guy combined the Thorley y-pip and the end of the stock y-pipe:
The y-pipe doesn't have catalytic converters. Other than that, and dealing with the fabrication to make them work, the kit is remarkable. I have only driven around town today but I keep noticing that the Tahoe has better power under 3000.
The two things to look out for are the driver-side header hitting on the body and the passenger header hitting on the heat shield that sits underneath the air conditioning equipment. I highly reccommned these headers. I'll be making a road trip this weekend and I'll post what my mileage is once that trip is over.
