I have a good 66 coupe, stock condition with 289. time to replace the exhaust manifolds,,,, left cracked and right on it's way, so doing both. checking some parts websites, i see the exhaust as it exists, and then tri-y headers.

can i go either way? are any modifications required, and what would be the benefit of one over the other - parts catalogue says about "improved performance and gas mileage". thanks for help!

 

first, welcome to the site!

you will see performance gains by switching over to headers, there are short tube, long tube, and tri-y headers available. generally, the shortys are considered a waste of money. long tubes are best, and tri-y's are basically reconfigured long tube headers that are supposed to work the best. also, ceramic coated headers are considerably more expensive, but they look nicer, last ALOT longer, and will help keep the extra heat headers inherently bring under the hood to a minimum.

you WILL have to modify you current exhaust pipe under the car to line up to the new headers though - if you dont have a decent set of pipes this would be a great time for nice dual exhaust with a crossover pipe (either X or H pipe, X is best) and some hi flow mufflers. current muffler designs will pretty much mean one brands cans will perform about the same as anothers, the main difference is in the sound each companies muff's will provide. flowmaster and magnaflow are probably the two most popular brands.

of course you could keep things stock and just replace the manifolds, but how much fun is THAT??

 

i am actually curious to see the diff on a something similar to a dyno sheet of the differences on between the stock manifolds the hipo manifolds and headers cause if there isn't much from hipo manifolds to headers i think that i am gunna invest in the hipo manifold because i have alot of the hipo stuff on/ in my engine

 

I agree with my77stang's suggestions. I have a 66 coupe and I am running Tri-Y headers which are ceramic coated and 2.50" exhaust including H-pipe with 2 chamber Flowmasters all the way to the rear valance.
I am not sure if you want the car crazy loud or if it's not really modified, you may want to go with 2.25" exhaust instead with an H-pipe and quieter mufflers like some Dynomax mufflers.

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