generally the most "accepted" route for improving performance seems to be:
Intake
Pulley (if 178 or code3)
Engine tune
NW mani's (engine WILL need retuned, do at the same time as tune if you can)
Downpipes/cat removal
Other goodies that should be sprawled throughout as needed:
Supercooler
Intercooler seperation kit
Meth injection
Valve covers(might as well get them teflon coated if they start leaking)
Modified Throttle body
Modified Thermostat
Blue top transmission solenoids (I have no clue where to source these, someone chime in?)
Resonator removal or full catback setup
Upgraded Turn signal blinker fluid
Drag Radial setup
LSD (if we can get it going...which we need....jab to everyone reading this, you know you wanna.....)
Nitrous
Pulley saver kit
Gauges (common being wideband afr, iat, boost, egt, oil pressure, 02)...or just get a zeixtronix zt-2
POSSIBLY woody might have a crossover design for some people to try on their mani's....I know i'll be one of them.
This car is proven in for the 11's with a good driver and a good engine tune. Take your time, do it right, and measure 182329108 times...cut 1/2...then measure a few more times, then finish the cut.
On the other hand, if you just wanted the nicer sound first off.....go with a magnaflow 16633 catback and call it good 