Doug Thorley Headers Installed, LOUD Sierra!!!!

Waterfowler41 · June 6, 2017

Morning!

My latest review project: Doug Thorley Tri-Y Headers. There is a lot of talk about headers on this forum but I couldn't find much experience with Doug Thorley headers so figured why not check the headers out and provide some feedback on them. Their design intrigued me.

First and foremost these are a different design than the typical 4-1 headers we are all used to and frankly they seem to be the only ones I know of making the 4-2-1. The DTH headers are a 4-2-1 design or tri-y which results in middle of the curve torque and HP gains which in my case on my daily driver (60-80 miles a day for work alone) was much more useful power than top end gains like the 4-1 provide. This concept has been around forever but seems other manus. seem more inclined to the 4-1 design.

Since I was planning to make the video and post here the DTH folks provided a coupon code for me to share in the event you want to take the dive into their products. The code expires July 5th more details in my video.

So my thoughts:

Pros- Completely possible to do this install in your garage but take my advise, GO THROUGH THE WHEEL WELLS. I am not sure why none of the major header manufacturers say anything about this but damn did it make life easier. The overall install was a piece of cake. Everything fit without any modifications needed or special tools. My truck had 50k miles so bolts were relatively easy to remove. The welds and construction seems well made and didn't cause any issues during the install. Seat of the pants test, I think I can feel a little more power during some hard pulls (may just be placebo affect). A tuner will open that open more and solve some of the "cons" issues below..

Cons- 8 hours to install in my garage with a friend helping half way through... These are catless so they are loud and with my SW catback (s-type mufflers), even louder. Half of my commute each day is through town so I throw a bit of echoing noise off the builds and in parking garages. No cats means my exhaust stinks and in rush hour with windows down it does get to you. The final observation is after installing the truck seems to want to go to V4 mode a lot more now (every chance I am at a steady RPM) I suspect because of the CEL being on. A tune is absolutely necessary for headers even more for catless ones so add that into your header budget. Lastly for some reason in V4 mode seems like under 1,500 RPM the truck does vibrate quite a bit more. V4 rides a little rougher than V8 mode even before headers but the headers exacerbated it.

My wallet likes the AFM mode a lot but with LT headers its probably time to say good bye to it.

Anyways enjoy the video. I enjoy making these so hope you guys are finding some value in them. Sounds clips are at the end...

- Waterfowler41