DP will open up the N55 -
it's worth doing.
if u had catless DP on ur n54 - shouldn't be a question.
the smell is the downside for most.
i don't know how emissions testing is for you but
something to also consider.
FrankiE90 AKA:.[The TANK] *CLICK THE SIG
E90s (been gone but not forgotten) • KW clubsports • • • • • • • • • • 18" BBS GT4 // Build E30 (pending) + E46 M3 Wagon ESTORIL Blue