A stock RalliArt is about 210-215 WHP on our dyno.
To get to about 260 WHP you would do:
Used EVO X FMIC $300
Install FMIC $200
RRE Axle Back exhaust $350 –or- RRE Modified Stock Muffler $140
EVO X BOV $180 Installed
Drop-in Cosworth air filter element $43
Tune with boost pill $400
The stock turbo is super super small. At 260-270 WHP the turbo is maxed out and other higher flowing won’t make much power, if any at all. You can upgrade intercooler piping, exhaust piping, cats, DPs and more and it won’t make noticeable power. The turbo wheels are the limiting factor at this point.
To get to 300 WHP you would need in addition to the above:
Used EVO X turbo, exhaust manifold and all install parts (usually a mix of used and new parts). $1000-$2500
List of parts:
http://clubralliart.com/showthread.php?t=351
Install Turbo Assy $600