Hey guys who has done exhaust upgrades and if so what have you done, have you had it dynod and how much power has been increased? Iv got my Nav chipped and am looking to put an exhaust on in the future but still currently undecided on what to do with it, and should see bigger gains with it being chipped aswell. Iv also noticed that since having my nav chipped it blows out a fair bit of black smoke, wondering if getting a bigger exhaust will help reduce the amount of smoke.