I heard the stock ac lines are prone to leaking so I would recommend all new lines and fittings. I have not been running one on mine and I justify that because I am not autoX racing or pulling an extra 1000-1500lbs of weight (cadillac body)
If you do bypass the oil cooler I recommend the West Coast Fiero kit. I think it was $25 and they give you instructions, the fittings, and a special drill bit that wont bite into the oil passage when you drill it out larger. Definitely drill out the passage if you are bypassing the cooler. Don't want to restrict oil flow.
If you call WCF, they are pretty good on explaining the reasoning and function of their parts. They are a little bias because they want to sell you parts but they give you enough information that you can reach your own conclusions.
1988 Notchback 4.9 V8, 5spd Isuzu, Spec Stage 4
True Dual Exhaust, Delta Cam
1993 Ford Probe 2.slow 5spd
1996 Grand Am 3100
2001 Honda CBR 600 F4i
[This message has been edited by arte444 (edited 03-28-2008).]