I've run the 1/2 mile with 255's on the front and 225's too. .01 difference. With the passenger seat and without. Couldn't measure a difference. Street tires and drag radials. Traction is non existent on runways so no difference I could measure. I felt like my car died in 4th but that's where I pulled, or lost less ground with the car in the parallel lane. I've taped all the seams and run dirty. With weight taken out, all taped up, race gas, drag radials, spinning all through 1rst or not. One or two mph max difference. Nothing will show the horsepower your making more than the 1/2 mile. Trust me, the best test you can do to know where you really stand. Doc, all you really need is the wide band and if you run with Sunoco 104 13.5 is safe. Ask me how I know.

Les