As far as your exhaust is concerned, you probably just killed some low-end torque. That'* way too open for your car. Even the SC models don't benefit from that. Staying 2.5" and using a performance cat and muffler would be best.
The chip is a good bag of worms. Jet stopped making the best chip for you, but they still make them for the SSEi. Your options are down to fastchip, superchips, and hypertech.
Bummer. Turtle has the Jet Stage 2 like I have, in a 92 SSE with a Series 2 motor. He loves it almost as much as I love mine. It'* possible you may find one used or old stock somewhere. I'd look around ebay. DON'T fall for the cheapo fake chips. Stick with the names I listed above.