My old pump gas street Duster ran right at .02 ET (6.99 with them off ) quicker with a .2MPH (95.4 VS 95.2 MPH)increase in the 1/8 mile by removing the full length 3.0 inch exhaust with a set of Magna Flows 14x7 oval with three inch in on the side and out the center no baffles at all mounted at the rear bumper shruggy work
That car ended up running a best of 9.993 at 134.7 MPH in the 1/4 with me in the car weighing 3450 Lbs. through that exhaust system.My message is you may not see any gain, maybe some luck The only real way to know is to try it scope up

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)