Question for PA stangers

Im moving from NJ to PA this summer and im planning to try and get my 89
mustang registered as a classic. Ive been reading the state dmv website and basically it says the car has to be in good condition and mostly stock. Right now it has shorty headers and still has cats. Before i move out there im putting on Lt's and an o/r h-pipe. My main questions are:

Should I have any problems getting it registered with some mods.

The site says that cars registered as classics are emission exempt for visual and the sniffer test but, will it have to be tested before it is given the registration?

Thanks :SNSign: