yes, it's an add-on. my mod objective's not to make it look like an updated 02+ necessarily, but rather just enjoy a preferred design line. overall i thought the pre-02 rear valence itself was too narrow in height. when looking at the car diagonally from the front towards the back, I always thought the 91-01 rear section of the car looked slightly effete and atrophied (and sometimes not even there)! the new valence increased the vertical distance from the bottom of the valence to the top of the trunk line beefing it up, filling it out and making the car appear more stout. others on prime have commented on this before. however, the horizontal strip on the back i personally never preferred as i thought it took away from that low, flat, lemans-race-car kind of feel. i did like the mesh upgrade, but that was hardly as noticeable in comparison to keeping the other visual effect of being low, flat and wide. all i wanted to achieve was a sturdier profile while trying to keep the back the way it was...so yes, those are 02 spats and a rear diffuser painted black.
<img src="http://www.vf2ss.com/transfer/rear_valence_compare.jpg" border="0"/>
( ^ pulled this from google images just for reference and my car on right)
just my opinion: i think the original rear looked wider and flatter than the update.
<img src="http://www.vf2ss.com/transfer/rear-comparo.jpg" border="0"/>
( ^ pulled these from google images for reference)