Hi, i have done these mods recently.
I used a grinder to cut the small amount of metal from the bolt holder. the 4motion valance was a bit of a git to get on, just because of the excellent VW fit.
Honestly Milltek cat back on my 2.0 8v sounds fantastic and the fit is second to none, mine is the twin tailpiece.
well worth it,

email me if you need any pics or advice
