Hmmm, bigger throat, bigger exhaust, seems like the delicate balance will be disrupted. i think you will probably need the waste gate ported. I went 2-1/2" cat back as my only mod for a few years and my boost would creep in cold weather. So when my turbo died I went all vj11 hybrid and ported the gate to 0.87" and said goodbye to spikes and turbo lag with the hybrid. Nice powerband even though I still have the stock intake otherwise. You don't have to go hybrid, but the bigger exhaust usually bothers the waste gate. If you are not planning to port the waste gate I would strongly suggest your exhaust stay under 2-1/2". I thought I could get away with it but it eventually got me.