RPM
WARNING: Apparently the pictures on this page are nicer than how the actual pieces turn out. Please be advised you should ask THEM for pictures before ordering. It should be noted that turnaround time could be months also! I am not affiliated with this company in anyway.
RPM Makes the following for the MKII NA (5S-FE):
Equal Length Headers (removes primary cat)
Ram air Intake (using the side vents)
For both the Turbo (3S-GTE) and NA (5S-FE):
Custom replacement A-pillar for gauges
They also do custom work from exhausts, to down pipes, to full race cars!
For custom, fine handcrafted performance parts call Will @ RPM in San Diego: 619-464-6128. Let him know what you want! They accept Visa/MC too!