This is just my opinion, so take the free advice for what it is worth.
The Stage 1 & 2s are little more than body kits with a little suspension stuff thrown in.
I don`t think they are worth the extra money.
You could use that extra money on mods to make a GT into a pretty hot puppy.
The Stage 3......thats a different matter.
I think its ugly but, it has serious power mods.