When drag racing my 535, I run max @ 6800 (rare that I twist it this hard) and during road racing I max at 6200. The most rpm the motor has ever seen was when I was teaching my wife to drive it and she downshifted from 4th to first rather than third--probably 7500 or better. Motor held, but I certainly would not recommend it! In normal street driving I can't remember ever going past 6000 or so, and that very rarely. In a normal street motor, spirited driving or stop light Gran Prix should not need more than 5000 or so., which is well within the range of a decently built inexpensive street motor. Only real alteration that I strongly suggest is a hi volume
oil pump and an extended capacity
oil pan. A good insurance policy would be twin
oil filters and an oil cooler if you plan to run hi rpm for extended periods--more oil in the motor never hurts!!
