On my 1999 Mustang Cobra so far this all the go fast goodies I've added:
JLT Ram Air Induction, it's pretty nice I just pop out the passenger side headlight assembly, simple as pulling the retainer bars and disconnecting
the headlight connector (all tool-less) and it gets a straight shot ram air effect for the track.
Steeda underdrive pulleys with SFI approved dampened harmonic balancer.
Custom Diablo Sport tune.
BBK short tube headers (ordering a set of long tubes and selling my friend the short tubes for his 4v motor swap).
Full exhaust with flow master 40 series, no cats.
Maximum Motorsports Aluminum clutch quadrant, firewall adjuster, with stock cable (stock cable is one of the most durable and reliable cables you can
MGW short throw shifter, I love that shifter it's a night and day difference between the stock slosh stick and this shifter, it practically jumps
into third and has the perfect throw and a very nice positive engagement.
TR3650 trans swap.
I have a full Derlin IRS bushing kit that I'm waiting until spring to install as it is a pretty big job but they make a massive difference in the
handling of the car and get rid of the annoying "Cobra Clunk" from the Ford NVH team going over SVT's head and replacing the bushings with much
softer ones to help with noise vibration and harshness. The Derlin bushings are well work a little extra noise though.
Also have H&R race springs ready to be installed when spring roles around too, will be ordering Caster/Camber plates soon too.
SPEC Stage 2 Clutch Kevlar friction material Street/Strip rated at 530ft/lbs of torque and still very mild on the street.
Soon to be ordering Steeda bump-steer kits front and back.
I also have a Maximum Motorsports full length subframe connector set.
Steeda button head IRS subframe bolt kit to allow the use of 315/35R-17 meats in the rear, can't wait to throw a set of these on the back and help
remedy my severe traction problem.
Saving up the money for a Kenne Bell Big Bore 2.1L supercharger.
I know I'm forgetting some things but you get the point.