If your looking to put springs on, there is a shop in Philly. The place is Custom Toys, they did mine and a few other guys in our group. There aren’t many people doing anything to the motor other than a tune by sending the ECU out or piggyback which is a DIY deal. If you order an exhaust set up most shops can handle the install for that.What are you looking to have done?
There is a shop in Chichester PA who is a Stinger owner and has done work on many Stingers. The owner Brian is a Master Mechanic and does great work.