I'm planning on buying a 2017 or '18 convertible and doing enough mods to get it into the high 12s. From my V8 performance days, a quality aftermarket "catback" would generally be good for about 10HP. Don't know how restrictive the EcoBoost exhaust is but I'm willing to give up a few hp to keep the car fairly quiet. I'll consider an aftermarket catted downpipe if it's required for a more aggressive tune. Is anyone running most of the bolt-ons with a stage 2-3 tune and stock exhaust?