Didn't you know... Stock is the way of the GP! Do not wander from the path. Copy the herd. LOL. If you choose to though, DuBoB's GP is one beautiful car to go by.
Do or have quality work done and modify everything. There are numerous kits out there for the GP, but none are my taste and I helped make the first one ever available for the 97-03 GP (no creative control though).
Nothing out there you like, make your own... I am if I can ever get that last pieces I need for the fascias.
Many of the kits out there are poor quality, so you have to be careful with what you buy. The cutout kit looks pretty tight though. LOL.
I can't deny what other's have stated, if you get an SD air dam, hood, spoiler, etc. it will still look badass. Good luck on your search.
