I just got my car back from Doug Thorley Headers and thought I'd share my thoughts. First thought-WOW. Like the rest of you I was looking for ways to get more power and make the car sound as good as it performs, naturally the exhaust system was one of the first targets. Not wanting to go the way of the $66 exhaust mod or creating a resonating chamber of the interior, I contacted Doug Thorley Headers and asked them about there plans for developing a system for the G8 and they jumped at the chance.

I'm extremely happy with the new sound. Deep but not overwhelming, only a slight change with regular driving (yeah, like we drive that way)but it lets you know it a V8 when you nail it!

They did a truly professional job (as you would expect from a world class company) with the components they developed for the G8. The engineering and testing of the axle-backs addressed not only the much needed sound improvement, they gave careful consideration to cabin noise (the dreaded drone) and the effect AFM/DOD has on the system. I've been able to put a few miles on it and don't have any complaints.

In addition to the axle-backs, they also developed a set of long tube headers! I managed to get the dyno results and was amazed to see they got 24 hp thru the stock exhaust! They told me they were also prototyping a set of shortie headers! Looks like they think there's alot more power to be gained from the exhaust system mods.

I've included some spy pics and the dyno results for the header pull and will post additional info as this project progresses.

Here are the additional pics and dyno results.

So the dyno you list is for long tubes and exhaust vs stock?

And the first long tubes for the G8 :thumbsup:

Oh nice.
I don't even have my G8 yet, and I have so many plans.

So the dyno you list is for long tubes and exhaust vs stock?

And the first long tubes for the G8 :thumbsup:

Dyno results are for the long tubes and the full factory exhaust. No intake system mods, factory air filter. No tune, just the headers.
Impressive gain under those conditions...

Dyno results are for the long tubes and the full factory exhaust. No intake system mods, factory air filter. No tune, just the headers.
Impressive gain under those conditions...


So what were the gains with the axle-back and headers?

Those headers may work, but they are ugly as sin - might want to get them coated at least.

The axle back looks fantastic!

Very impressive. You know the next question... how much are these going to cost?

Chilly, I'm sure those are just the prototype headers they built so they can make the jigs, bend numbers, etc for the production headers. Especially with a company as large as Doug Thorley, they will most likely be cleaned up a lot.

Dyno results are for the long tubes and the full factory exhaust. No intake system mods, factory air filter. No tune, just the headers.
Impressive gain under those conditions...

thank you for the reply. Did you get any dynos for the cat back with stock manifolds or headers?

Also just so i am clear. The "axle back" system, means just the replacement muffler/tips?

What's up with the metal tack-welded around the mufflers?

What's up with the metal tack-welded around the mufflers?

It appears they made the mufflers from scratch for this project and they made them to fit.

Aluminized or 304 SS? All the mufflers shown on the website say aluminized. Its hard to tell from just the pics because while the muffler case and piping appear to be aluminized, the dark black soot around the tack suggests tri-mix gas which is used for welding stainless.

Looks like they have chosen to run the mufflers higher in the heatshield pockets as well.

Nice work, I hope you enjoy the new sound!

S.F.

Cool...Headers!

I assume those are your stock tips added to the end of the axle back? Looks good.

Sound Clips!?!?!

Please!!!

Tri-Y's FTW!

did you get it done in corona?

I like those tips! They look bigger then the stock ones which I think they should be anyway. Now we just need some sound

Do the headers retain the stock cats? If not, did you use high-flows or go catless for the dyno run?

throw some ceramic coating on the headers and you're done!!

I think i will be waiting for Kooks to make some stainless ones

test

test

The answer is 42. Did I pass? :)

Hey all, just thought I would drop by and say hi and answer a few questions. I can't talk price or delivery until we are a paid vendor on this site. This will happen as soon as the admin replies to our request and takes our money.

The pics you see are prototypes and you guys and gals are the first people to view them. The production units will be fully mandrel bent and will come ceramic coated as a standard feature. The primaries are 1 3/4" and the secondaries are 2". The headers are true long tubes and delete the cats. You will not need to purchase O2 sims or extensions. Besides the obvious gain on the dyno, these headers really made a dramatic improvement in the "seat 'o the pants meter". I had a blast testing it. Sorry Dan, the temptation was strong:p.

The axle back consists of our very own mufflers and four 3 1/2" slash cut tips. The mufflers will be coated with a special high temp black paint and the tips will be triple nickel, chrome plated stainless steel. I would be happy to answer anymore questions you have, just pm me.

I also would like to thank Dan (filterman) for his generosity and look foward to working with him again real soon. Thanks Dan!!!

Jamie Joyce-Doug Thorley Headers :gears:

Hey all, just thought I would drop by and say hi and answer a few questions. I can't talk price or delivery until we are a paid vendor on this site. This will happen as soon as the admin replies to our request and takes our money.

The pics you see are prototypes and you guys and gals are the first people to view them. The production units will be fully mandrel bent and will come ceramic coated as a standard feature. The primaries are 1 3/4" and the secondaries are 2". The headers are true long tubes and delete the cats. You will not need to purchase O2 sims or extensions. Besides the obvious gain on the dyno, these headers really made a dramatic improvement in the "seat 'o the pants meter". I had a blast testing it. Sorry Dan, the temptation was strong:p.

The axle back consists of our very own mufflers and four 3 1/2" slash cut tips. The mufflers will be coated with a special high temp black paint and the tips will be triple nickel, chrome plated stainless steel. I would be happy to answer anymore questions you have, just pm me.

I also would like to thank Dan (filterman) for his generosity and look foward to working with him again real soon. Thanks Dan!!!

Jamie Joyce-Doug Thorley Headers :gears:

Can you explain why the primaries are routed into the first "Y"s in different order (drivers vs passenger side) in relation to the cylinder order? The passenger side is in the same order as the cylinders however the drivers side is not. Is this for packaging purposes or does it have to do with the firing order of the L76 and scavenging in the Tri-Y layout vs. a single large merge collector?

http://i152.photobucket.com/albums/s190/angelajeanmessina/headers.jpg

S.F.

The primaries are 1 3/4" and the secondaries are 2". The headers are true long tubes and delete the cats.
OK - stupid question here.

You're deleting the cats (catalytic converters)? How will someone get their vehicle to pass a smog test/inspection without having cats? We can't do that here in Atlanta yet alone California.

Been there done that with a 67 442 when I lived in Sacramento. What a pain to get it smogged! And that was just headers and NOT deleting any part of the smog required equipment.

OK - stupid question here.

You're deleting the cats (catalytic converters)? How will someone get their vehicle to pass a smog test/inspection without having cats? We can't do that here in Atlanta yet alone California.

Been there done that with a 67 442 when I lived in Sacramento. What a pain to get it smogged! And that was just headers and NOT deleting any part of the smog required equipment.

they are gonna produce some shorty headers as well as the current longtubes..

they are gonna produce some shorty headers as well as the current longtubes..

Hey Russo - have you ever had your exhaust system inspected when getting a vehicle inspected in LA? In 27 years of Louisiana car ownership, I have never had the exhaust on a car visually inspected or fume tested.

Hey Russo - have you ever had your exhaust system inspected when getting a vehicle inspected in LA? In 27 years of Louisiana car ownership, I have never had the exhaust on a car visually inspected or fume tested.

They do out here.

OK - stupid question here.

You're deleting the cats (catalytic converters)? How will someone get their vehicle to pass a smog test/inspection without having cats? We can't do that here in Atlanta yet alone California.

Been there done that with a 67 442 when I lived in Sacramento. What a pain to get it smogged! And that was just headers and NOT deleting any part of the smog required equipment.

Yup, lost my interest right there as well. AZ and NY are getting just as bad as CA.:banghead:

OK - stupid question here.

You're deleting the cats (catalytic converters)? How will someone get their vehicle to pass a smog test/inspection without having cats? We can't do that here in Atlanta yet alone California.

Been there done that with a 67 442 when I lived in Sacramento. What a pain to get it smogged! And that was just headers and NOT deleting any part of the smog required equipment.

These are for off-road use only. A smog legal version is on the way. These are for the drag racing and track day crowd.

Why did you have to get a '67 smogged? That must have been some time ago..

Hey Russo - have you ever had your exhaust system inspected when getting a vehicle inspected in LA? In 27 years of Louisiana car ownership, I have never had the exhaust on a car visually inspected or fume tested.

never, tint is the only thing i would worry about...

Why did you have to get a '67 smogged? That must have been some time ago..
We left Sac in November of 93. It was a regular thing until we left. Most of the time a smog tech would open the hood, then they would just close it and say "Headers are illegal..."

It was almost impossible to find someone who knew it was legal for a 67 442 to have headers without AIR (Air Injection Reaction). My 442 was an out of state car and didn't require AIR. Although I do have a complete AIR system if I every need it.

Now if I could only get my G8/GT to shift like the Turbo 400 in my 442...