THe previous owner of my car installed an HKS Super Drager exhaust, it has 65 mm piping (2.56" i believe)..I want to turbo my KA eventually, and I was wondering if I shoudl keep this exhaust or just get a 3" BRM. My power goal is between 250-300 whp, limited by the fact that its a daily driver and needs to be reliable, I can't afford standalone engine management or full forged internals, and I already have an ACT street clutch thats only rated for 267 WTQ. So...will this be a decent exhaust to leave on?

Also, I was lookign under the car and it looks like there is a cat, another cat, a resonator, and a muffler, in order from engine-->exhaust tip. What is the diamter of the piping between the 2 cats? Did the exhaust replace that part?