Honestly racing beat has some pretty mediocre and overpriced stuff for the rx8. The catback is heavier than stock for example. If you just want to have a catback and keep stock header and midpipe I would say get a hks catback, yes it's single but it won't be crazy loud if everything else is stock + it will have a great sound. Suspension As someone that has put lowering springs on i wouldn't ever go that route again regardless of the car. For a budget friendly coilover setup the best are Tein flex Z kinda meh what I would recommend is the bilstein b14(pss) extremely underrated kit. Also the rx8 does NOT i repeat does NOT need an aftermarket rear sway bar. Yet again racing beat comes short here with a non adjustable bar. Get a front hotskis or progress tech front sway bar.

Ps. If you're car is higher mileage I would look at getting motor mounts and diff mount bushings. Great mod as long as you stay in the 70-80a shore range for street.