After years of being (relatively) satisfied with the 400G in my '69 442, I've pulled the trigger on Mark Remmel building a 455. When I drop the new engine in the car, I will be switching over from the current Thornton short tubes to a set of proper long tube headers. Needless to say, this forum, in addition to multiple other venues, is littered with horror stories of poor fitting headers having to be dented and 'persuaded' to fit. I hope to avoid as much of that as I can. The car has a/c, ps and the TH400.
I currently have a 2.5" stainless steel exhaust system on it (which I'll retain). Mark informs me a 1.75" primary tube header will be sufficient for the build so I've been doing research on what's available and also what's been problematic for the community. Based on an older post about a set of Doug's, I've ruled them out completely and have narrowed my list down to two: Hooker PN 3902-1HKR and ARH PN OBBA-64178300HR. The question I'd really like to get an answer to is whether any of you have experience with the Hooker's in a '69 (or '68)? What problems, if any, did you encounter? Their reputation is pretty good so I wouldn't expect any surprises.
If money were no object, I'd go for the ARH's. I don't necessarily need the 1 7/8" primaries but I like the fact that they're stainless, their reputation is top notch and there seems to be few complaints regarding fit - although I question if maybe there have been issues but guys tend to overlook that because of what they pay for them! However, I have a hard time trying to justify the cost. They're easily twice as much as the Hooker's. If this was 1975 and the car was a daily driver I might reconsider but given how much/little I drive it, the Hooker's will easily last for the next 20 years.
I haven't found any installation horror stories (yet) on the Hooker's but if you have one, now's the time to spill your guts. Thanks in advance for any replies.

 

I bought a set of used Hooker headers that had been installed and run on a similar year car so the tubes were pre-dented in all the right places. I talked to one of the coating companies (Jet Hot maybe?) and they said they would have no issues coating used headers, so I wouldn't be beating up on the coating to get the tubes to fit.

 

The hooker 1 7/8 headers fit my car very well. I did t have to dent or massage anything.

I had previously relocated the brake distribution valve using one of the bolt holes for the clutch bracket. That would have been the only headache.

 

I FINALLY got my ARH! I haven't put them in yet, though. I'm replacing the Hookers. They needed clearancing around the steering shaft as well as the passenger, rear upper control arm.
Now, I have some Smitty-fabbed solid motor mounts, so I can't really say how much difference there is between those and factory units, height-wise. I can say that I have not had good luck with ceramic coating; it always gets scratched and starts to rust. For that alone, i am looking forward to the ARH stainless.

 

I'm running the Hooker 3902s in my '68 4-4-2 4-spd. 3" collectors into new 2.5" piping to the rear. I just realized that I misremembered the install in another thread. I DID have to exercise a bit of creative fitting over the top of the bell-crank. That was before I installed new motor mounts. After the new motor mounts were installed, there was a little more clearance over the top of the bell-crank. I did not have any other fitment issues. Not around/near the starter, nor on the other side, near the oil filter fitting. Those sides were perfect. - close fitting, but no interference. With your TH400, and no bell-crank, I'm guessing you'll be alright. Oh, and mine had been in a front-left fender bender with some previous owner, so my frame is just a hair off, as is fender, hood, and core alignment. Whatever shop did the work did darn good work.