Quote Originally Posted by jbright300 View Post
How much HP and torque drop will 1 1/2" long tube headers have.....at 3500 RPM?

"Dropping down to 1 5/8" on the header tube size drops 5 hp and 3 ft/lbs of torque, so if it's easier to fit the smaller tubes, I'd do it. DO NOT GO ANY SMALLER THAN 1 5/8".
1 3/4" headers 463 ft/lbs @3500
1 1/2" headers 433 ft/lbs @3500

You choose.