Header Recommendation
 

I have a set of rusty, unknown-brand headers on my '65 GTO. The motor has D-port 6X heads. I want to replace the headers with a new set. Can anyone recommend a brand/type of header that they've had good luck with in this engine/chassis combo? This is a purely street-driven car, so I don't need anything exotic. And I'm not really interested in going back to stock HO manifolds at this point, even though I realize they'd be less maintenance and have more oil filter clearance.

TIA for any advice!

Dougs Headers have been the go-to for quite some time.

Good ground clearance for a 4-tube header and the fit is good as well.

I have the Doug's D564 D-port headers on my '66, which fix excellently with great ground clearance. They should fit into your '65 just as easily. Remove the starter on the driver side and the oil filter + oil filter adapter on the passenger side and they go right in from underneath. To aid tightening a few of the bolts on the driver side head, it helps a lot to simply remove the driver side engine mount bolt and tilt the engine up a few inches. That will give you the access you need to tighten the bolts on that side without fighting for clearance with the steering column.

But Doug's headers with Remflex gaskets are an excellent combo. They fit and work great.

I use Dougs. Have had 2 sets on my last 2 cars, both round port style, both '65 and '67 LeMans. You can make it easier on yourself by ordering ARP hex head bolts which accept a 5/16" wrench, and by cutting the flanges between the center and end ports. These 2 things help immensely in accessing the bolt when tightening. BTW, Remflex AREN'T the only gaskets that work and seal.

Have you considered having your current headers sent out and coated, recoated? Doug's headers are EXPENSIVE.

They’re $1000-$1200. EVERYTHING’S expensive. Pontiac enthusiasts are some of the cheapest MFs I’ve ever encountered.. 🙄

I have "roundport" Dougs on my 67 GTO. The fit is excellent as is the ground clearance. Prior to that I had Hookers and they hung pretty low.

Hedman makes nice headers that arent as expensive as dougs or hooker super comps. They fit & seal up nice on 2nd gen firebirds, never heard anything bad about them besides how most people hate installing any header.

I generally agree. Pontiacs parts are more expensive than a Chevy or Ford, but they're not expensive compared to a lot of other collector cars. I also play with old German cars and they make Pontiacs look downright cheap to fix up.

That said, the price of the Doug's D564 headers that I have on my '66 has increased 40% since I bought them four years ago. But as you say, everything has gotten more expensive.

Building a 421 for my 65 GTO right now and plan on using Doug’s headers. I’m curious as to what exhaust system is everyone using with headers and still be able to use the factory looking exhaust splitters that exit behind the rear tires.

I’m using a 3” system on my ‘65. I didn’t really consider splitters, because I doubt they come large enough to fit onto a 3” tailpipe. Guessing they only come in 2-1/4 or 2-1/2, but someone that’s scoped it will likely chime in.

I have a 2-1/2” Flowmaster H-pipe system with 17749 Dynomax Super Turbo mufflers. I had another set of tailpipes that I used because it was impossible to separate the turned down tailpipe extensions from the tailpipes.

I fabricated the 2” splitters and bought some reducers that I had welded to the splitters. Then I was able to position them at the angle that looked right to me, the hanger clamps retain the splitter tips. I had bought some reproduction splitter hangers that ended up working nicely even for my non-stock parts.

More pictures.

The 421 HO in my convertible is essentially stock with a slight drop in compression, running the stock log exhaust manifolds. It’s probably a 350 hp engine at best and does fine with the 2-1/2” mandrel bent exhaust and the 2” tips. Sounds pretty civilized which you need for a convertible, but the Tri-Power does roar loudly whenever the opportunity presents itself.

I’ve also done a complete 3” hand fabricated exhaust with 3” splitters (with stone shields for burnouts) all in 304 stainless. Not exactly civilized, super loud with race Flowmasters and later toned down a little with Pypes Race Pro straight through mufflers.

Thanks B-man. I have a Magnaflow system on my 69 Firebird and like the sound. Figured I’d stick with Magnaflow for the 65 unless someone had a better suggestion. Looks like either way I’m going to have to get creative and do some fabrication.