As far as retrofitting these heads to 03 & earlier models go, there are some things to be aware of:
•The fins on rubber mount heads are a little larger than the fins on the earlier heads, so they won't match up to your cylinders quite as well. It's most noticeable on the left (spark plug side) but most people don't think it looks bad at all.
•The front motor mount bolt holes are 7/16-14 (like the Buell heads described above), but also the right front bolt hole (pushrod side) has been moved inboard 1/4". A special bracket is readily available from HAMMER PERFORMANCE to take care of this and allow you to bolt the heads right on to your 03 or older Sportster.
•As delivered from the factory, these heads are .020" shorter than the previous generation heads, at 3.670" instead of 3.690". Normally this is not enough to worry about with respect to pushrod length and manifold fit. However if you're shortening the motor further via thin gaskets or further decking, it's something to be aware of. Once you've shortened the stack by .045 to .050" overall you need to be thinking about these things.
•None of these late model heads are available from the factory in an assembled form. You have to buy the heads bare and then buy the valves, springs, retainers, locks, and guide seal/locaters separately and do the assembly yourself. However, HAMMER PERFORMANCE sells these heads fully assembled and ready to bolt-on for the same price that the heads and hardware will cost you at your dealer. We'll also include our special High-Flow Swirl Polished Stainless Steel valves instead of the cheap factory valves, again at no extra cost!
You will need to tap breather bolt holes/ carb mount bracket as they are not tapped onthe xb. I drilled and tapped a set off of an xb9 to run on his sportster.
I would tap them for Carb support only, but not drill them through for the breather. The buell rocker covers already have pcv valves in them, a far better vent system than the sportster/early buell setup.