I am looking for advice on a brake upgrade. I have the DD bullits from mustangtuning.com and want to make sure I get some good brakes but will also fit under my wheels. My stock brakes look really close to the wheel already but I want to be able to stop if I need it...I'm about to install my s/c so I might need a little more stopping power than stock

 

well, since you have 18s, you probably arent going to be able to fit a plus sized kit with ease. It might barely fit, you'd have to check specs. But you could definitely do rotor replacement, performance pads, and brake lines while retaining stock calipers. It will definitely help alot and will definitely not have any fitment problems with your wheels.

 

Many plus-size kits will fit under 18s, but you should check and see.

Hoses and pads are a good place to start. I am not a fan of stock-size replacement discs. I'd say if a pad/hose upgrade isn't enough, then find something with larger discs.