Im not sure about a N/A Maxima running 12's. but i can tell you that the 4.6 motors internal's **** ass. rods will throw quick. In a SOHC (GT) engine you best not go over 425 w/o meth injection. And with hte mods you are pushing, you should run a nice 13.5 in that area IF you can drive. I can tell you one thing, you need to call me so i can burn you a chip or set a Xcal 2 up for you with those mods to calculate for gears and such. you will prob run lil lean and your speedo WILL be off. STOCK MACH 1'S ARE RUNNING HIGH 12'S OFF SHOWROOM FLOOR!! hehe. I did it with like 34 miles on it. and the 03/04 cobra motors are almost bullet proof, they have a steel crank, and all forged internals. We have put 720 horses on a STOCK 03 cobra motor. Not many engines stock will take that.