I take it there are performance chips, headers, etc on the market?

The 85 US and newer can use a chip, the older ones dont need a chip as they have a good ole' fashioned distributer and pressure regulator.

The early cars can be upgraded with later S car headers, and they can all take MSDS headers(about 1000 bucks new, and good for about 30hp).

My two cents ...

Don't buy a 928 without a good professional inspection, figure on 3+ hours of labor, compression test, and a good amount of time on a lift.

Don't underestimate the cost of repairs. A nice looking, driveable 928 could have $25,000 of lurking repairs (rare, but could happen), that once done won't change the market value of the car by even 1/3 of the cost. This means if you buy a 928 for $10k that needs $9k in repairs, looking harder a similar car with the repairs already done might be $13k. It also means an offer of $4k might be appropriate if you like doing the work yourself.

PPI is always mandatory for one. Great advice. That's why I can't by off e-bay. Have to find a local one or one that I can get a fellow Pelican's help in having a PPI done.