I have an '02 P5, 154k miles and am considering doing two things in the near future to it. As of now, the car is bone stock except for a K&N drop in filter element. As for the two things I'm considering-
Since buying the car, I've always used Castrol 5w-30 oil and I regularly change my oil and filter. I'm considering using synthetic oil if there was a REAL benefit in horsepower or mileage, or protection. A salesman (!) at the local dealership said he gets big mileage gains in his perosonal Corvette by using Mobil 1.
The other thing I'm considering is chipping my P5. I saw an ad for SLR chips and they make some huge claims about horsepower and mileage gains and the chips cost somewhere about $60-70. I'm pretty skeptical of any huge gains, but what can I reasonably expect and which chip should I consider and what do they cost?
Mainly, I'm looking for mileage, reliability, and a few extra horses never hurt anybody...