OP here. I went with the SPM cat back to mate with my DP. Thanks all for input. Probably going to do wheels and tires next, both winter and summer. Winter are just going to be 16" steelies. I am struggling with th 17" vs. 18" thing with summer wheels. Going to start researching LSD's. If I was closer to a good tuning shop, water methanol would be next, but I am just too far away and WM sorta worries me.
yesterday I installed a hotchkiss rear sway bar and all I can say is WOW! I cannot believe how much better the car feels in turns. day and night. its much more stable and you can go in turns with 10x more confidence. I have yet to install my hotchkiss front sway bar or the DG springs I ordered. If the car feels this good with just the rear sway bar then I can't imagine how it will be with the front and springs. I thought the stage 1 tune was gonna be my favorite mod due to the night/day difference in power but i have to give the win to the rear sway.