the short answer is yes, it'll fit.

the long answer is that the heads are very different, as are the motors, and putting a dc-sports header on an HX is a complete waste of money no matter how you look at it. even if you're getting a rip-roaring good deal on the header, an EX head swap will cost about the same and might actually give you a gain you'll notice, instead of just making more noise and looking pretty under the hood.