Headers for the 403 - what to get

[lugnuts]

What are the best fitting long tube header for the 403? I currently have the Thorton shorty headers and I don't like them for several reasons but the main thing I don't like is the collectors are reduced down to fit the factory diameter exhaust creating a restriction.

I had originally hoped to get a set of the tri-y headers that Tribal tubes was supposed to make for me but he just stole my money and sent me nothing.

So that leaves me with whats out there and most of the options I see I know were never designed for the TA but other olds vehicles so out of them all which fit the best.  Are any designed for the Trans Am specifically or are they all adapted from others?

[MO 1979 TA]

I am curious to hear what people think as well. I am in the same situation and below is a list I created; however this is based on just research (reading). I have not personally installed any of them...yet. I have never heard of Patriot Exhaust before but viewed their product at speedwaymotors.com. The flanges look thick where it meets the block and they look like they are really well made for that price point. A front runner for me so far. Per your question, the American Racing Headers appear/stated they were purpose built for the Trans Am and the price reflects it.

American Racing Headers $1,513
Doug's Headers D570 Full Length Header $909.99
Doug's Headers D570-R Full Length Header $681.99 - raw steel
Patriot Exhaust H8301 Full Length Header $268.99
Hedman Hedders 58160 $391.39. Block hugger style. ?
Hooker Super Competition 3107HKR $655.95
Flowtech 31150FLT $472.95
Flowtech 11150FLT Long Tube Header $263.95

[Wallington]

The collectors being reduced to factory size would be worse if there was only one, not two.

[lugnuts]

The collectors being reduced to factory size would be worse if there was only one, not two.

if the motor was stock but mine is ~475hp so not sure having that restriction is good or bad but I would think its not helping anything. the other issue with them is the drivers side is leaking and one of the bolts can not be accessed with the motor in the car so at this point I'm going to swap them out for something better. I've decided to go with the American racing headers. should be here in a few weeks hopefully.

[mikebooms]

Selling the thorntons?

[sreta]

Do you have the first or the second version of Thornton's ?

[lugnuts]

Do you have the first or the second version of Thornton's ?

no idea I bought them in 2019.