However many more milliliters you want to bring the wheel out. Subtracted from your current offset
If you want 1.5" more you need 38.1 (1.5 * 2.54) less offset, so +3.4
There's probably almost nothing in there
i would remove it and just stick a breather in place of the oil cap
Or replace it with the UPR/Motion vented catch can if you want to spend some money
Would not be suprised if Whipple has to send their tune to Ford to get signed (by Ford) before it can be sent to any customers etc. I don't think Ford would allow Whipple to have a key sitting on their laptops waiting to get accidentally leaked...
If you're going by the OLM it will tell you to change the oil at 1 year no matter what. (not that you actually need to if you haven't driven the car much...)
Many people change the oil before 500/1000 miles (or both) to try to help get any break in particles out of the engine
I'd make sure you take it on a good high RPM run varying the load and then change it, especially if you have babied it for the 500 miles you have put on it so far.