i have an issue with header to ground clearance. i only have about 2 3/4 inches from the ground on the drivers side. they are hooker competition headers, not the shorties or super comps. they have 3 inch collectors that feed a magnaflow x pipe and full 3 inch pipes terminating out the back like the stock set-up. after searching for header options, the hooker 2466 shorties or the thorley tri-y's seem to be my best options. my question is concerning the thorley headers. they have 2 1/2 inch collectors. with all other things remaining constant, what will change with smaller collectors that dump into 3 inch pipes, mufflers, and tips? loss or gain in hp or tq, and where in the power band? the motor is a 383 with peak torque between 3k and 4.2k, dyno'd at 360 ft/lbs at the rear wheel with 325 hp at 6k rpm, rear wheel as well. should i go with the hooker shorties or the thorley's? or, header option #3: drive it till i break it, then worry about it! thanks in advance for your input!

What size are your primary tubes? I've used 1-5/8" primary tubes with 2-1/4" merge collectors and gotten great results. Our 331" road race motor made 363 #ft at the wheels at 4600 and over 415 rwhp at 7000.

What size are your primary tubes? I've used 1-5/8" primary tubes with 2-1/4" merge collectors and gotten great results. Our 331" road race motor made 363 #ft at the wheels at 4600 and over 415 rwhp at 7000.

they are 1 5/8" as well, 30" tubes. the thorley's and hooker shorties are 1 5/8" as well. only the length of the tubes and size of the thorley collector would change.

If you're going to go to the trouble of cutting off the old collectors and adding new ones, add about 10-12" to the length of each primary tube to bring the wave tuning into the power range of your motor. You can use this added length to move the collector up close to the chassis, closer than it would be if you simply added a collector to the existing tubes

There are several manufacturers of 1-5/8" x 2-1/2" collectors, including Headers by Ed, S&S, Chassisworks and LC Engineering. I used the LC Engineering parallel merge collectors because they were inexpensive at the time.

If you're going to use a traditional collector you should create the cross+entry like Ed Henniman makes. He claims it's good for some power.

You can also buy tapered tubing to create a smooth transition between the 2-1/2" collector and the 3" existing exhaust.