Definitely some great ideas here. I'd be all over OEM replacement trim pieces, interior panels, etc. Here are a couple that I didn't see mentioned, maybe I just missed them:
1.
A dual gauge pod for the 1G steering column like the one for the Evo:
2.
OEM quality headliner material. All the aftermarket stuff I've found looks cheap.
3.
Stock type suspension bushings. I don't want poly all around but can't find a good source for stock type rubber bushing. I have found some OEM style control arms for $120 that include bushings and ball joint, might have to go that route with poly subframes.
4. Already stated, but reasonably priced dual outlet 3" stainless exhaust. Most options out there (Vibrant etc) have 3" inlet dual 3" outlet and the inner muffler cores measure just over 2". This equals a 3" in cross sectional area but you have to consider the increased drag through the muffler because of the increased surface area. Magnaflow makes a 3" 2.25" dual out and dynomax makes a good 2.25"to 2.5" round tip which would be ideal.
5. It is probably isn't at all profitable but the fade decals on the 1Ga from the silver ground effects to the stock paint. No longer made, so if you want to repaint you car stock you need to leave them off. Doesn't look bad but not stock looking. Even better would be a good fade rather than the dots they used to make a fade effect.
There should be a sticky thread made for when any of these parts start to become available.
-Barra