Fuel map question for custom exhaust

I've got an 02 vfr that I will be installing a PC V and a modified exhaust that I recently picked up. The previous owner took the stock exhaust, cut at the end caps and removed the attached guts. Basically, when you look down the exhaust holes, you will see the mesh screen in the middle of the cans. The first half is hollow.

My question is what fuel map should I start with? I'm guessing the exhaust will flow somewhere between the stock cans and straight-through slip-ons. I know that adding an Autotune or taking it to a dyno would result in the best map but I want to wait until I've got the cash to add a full exhaust and then tune it properly.

Any recommendations on a good map to use as a starting point?

 

As long as the cat is still in place and in tact, the modifications to the muffler shouldn't affect the tuning that much. I'd say start out with a map for the stock setup, and work your way towards something for a 2-exit aftermarket exhaust. I'm sure someone else will be along with more information for you ..