Lol, even if you're a bad driver, you should still beat him.
As previous poster pointed out, he may be lying about his car not being stock.
In theory for every 100lbs, there's about 1/10th of a second lost.
Generally 135s do the 1/4 in 13.3 So that would mean 14 for a 535.
I then checked online at draglines.com and looked at stock cars, and those were roughly the numbers I found.
I wouldn't worry about beating him. Unless he's known for being sneaky.