If I was buying used it would have to be standard but thats just me mate. A standard P1 is excellent as it is, mine had the Prodrive 18s, P1 exhaust and Alcon brakes on it. A front mount is a serious upgrade and I would be wanting to see lots of receipts for the work done, remapping etc. I've heard that the MAF and the oil pump were common problems causing the rebuilds. I know of one P1 that had a rebuild and they never changed the oil pump and the engine blew again! If everything has been done by a reputable company and there is catalogue of history for it then all should be well. Its a buyers market at the moment so look at a few if you can.