I've done alot of mods since I've been to the track but, It's seems I run almost the same 60ft. with street or D/R's whats up? Do you heat your tires up? I've done wet burnouts/ dry burnouts and still about the same times.
Makes me wish I wouldn't of bought those D/R's & rims. The rims are a lil wider and the D/R's are 17's

 

Nitrous....with drag radials... problem solved about getting the same times...

 

I had the same problem. Im pretty sure its because I had a 275 on an 8 inch rim. I hear you get less contact patch than with the stock 245s. Also Nitto is just OK at the track if thats what you had. M/Ts are better......

I have just figured that the best way to go is to just buy some 10.5 inch rims and put some sticky 315s on the back.....