well, OP... if you end up just wanting an undertray let me know. I have a z speed aluminum undertray with a oil filter door that you open by just unscrewing two bolts... i've had it on my car for about 1k miles, but i'm getting rid of the car now so id be willing to sell it for a good deal if you want to trade me your oem undertray. feel free to PM me if you're interested.

 

My OEM under-tray is falling off. This might be the way to go.