yeah thats why i started this thread......lol. have a look at the apex site...ull see the N1 front pipe that im talkin about. how much is that N1 that u picked up anyways??
as for boost increase after exhaust fitting.......well honestly its alot smoother thru revs...less lag, but it doesnt have that anticipated kick that it used to when the stock exhaust was on. it probably is faster cause i wheel spin in second now but it doesnt feel any faster...just lounder....haha...plays with the mind abit. the front pipe should bolt straight on if its for a skyline that is and most hi flow cats and cats in genearl should fit. anyways this is the job of the exhaust guy fitting it in so u shouldn't need to think about it.
as for the aftermarket boost guage.....a definite if ur planing to boost it up. the standard one is abit dodgy if u ask me, doesnt really give u an exact reading. i fang it and the needle never hits 7 as its supposed too and im sure i dont have any boost leaks either.