i realize this might ruffle some feathers,but i believe that the guys at hot rod knew that they could make more power with hogged out stock manifolds than with off the shelf headers.one can buy cheap headers for 100 bucks,this would have made the build up still well under two grand.instead they spent two full days on the stockers.The stock manifolds look pretty much like shorty headers and are way more reliable.im sure that much after 5000 rpms tube headers are the only way to go but under 5 it might be worth the time and energy to hog the stock manifolds and probably be done with maintaince on that part of the motor forever.

 

The engine they were building had to pass CA emissions. That's the main reason they didn't use headers.

 

Years ago on a 289 powered Mustang Hobby class stock car we were limited to stock cast iron manifolds, both intake and exhaust. All we had was the old "log" style exh manifolds and they sucked! Even after porting! We found some 289HP {kinda looked like cast shortie headers} exh manifolds and ported them, MUCH better. We even found a higher rise 4 bbl intake, marine application, and that helped too. We were spinning the SNOT out of this little 289 just to keep even with the 327 and 350 Chebbies out there 'cause we we giving away so many cubes. A year or so later the rules relaxed a bit and they allowed us to use 1 1/2 primary, chassis exit, street style tubular headers and that really helped! We were just a bunch of hot rodders with a limited amount of $$ to spend so none of this is scientific, but the difference was noticable. The biggest pick-up came from ditching the log style and going with the HP style. 65-66 Mustang restorers would cringe at using 289 HP manifolds on a crappy old stock car! Anything to whoop up on Chevies! It has been my experience that tubular headers are the way to go if they are sized right for the intended use!

 

This has been discused before. 2 full days in a shop & your manifolds will have a unrealistic price tag on them at around 40$ an hour.Not to mention they will more than likely end up cracking.

 

point well taken. ive had some bad experiences with headers and was trying to rationalize not using them

 

I read in a Hot Rod a few months back (can't remember exact issue) a guy had a Buick GS Skylark that he got more power from modifying his stock parts than using any aftermarket parts, and one of those parts was ported and polished exhaust manifolds over tube headers.