how would i know what header you are even looking at? lol

As a general rule:
ALL USDM Headers will fit without having to cut the crossmember. USDM headers like Greddy, DC Sports, etc that have a 2.25 in collector

ALL JDM Style headers, meaning 2.5in collector, WILL NOT FIT without cutting your crossmember or running aftermarket traction bars. Headers include Hytech replica, Kiddracing, JDM 4-1 DC Sports or any JDM 4-1 replica, SSR, SMSP, etc

Basically any header that makes power requires you to mod or cut your front crossmember, its really not that big of a deal.

As far as bolting up to any exhaust you have, welcome to swapped EFs. Almost everything will take some form of modification