Who's done it?  How hard was it to do, or did you have it done?  Was there a noticeable difference in performance?  I'm about to rip into the top end to cram a bunch of go-fast stuff in, and this seems to be one of the last things ya can do.

Anyone wanna help a guy out?

There are many degrees of head porting,...  from smoothing cast marks to gasket matching, to computer flow testing....
I've done a few cars, and bikes... Nuttin' fancy,...
If you want to do a little,... that shouldn't hurt anything,..
get a Dremel, or I also use a ball shaped cutting bit in my drill,... (do only the exhaust,... roughness in the intake can more helpful than harmful, so leave it alone)... block the exhaust valves by stuffing some rag or paper towel deep in the hole, so no shavings get back there ... then gently, smooth the exhaust port passages,.. there is a torque hump that bumps up in there across the bottom of the hole,.. don't grind that away, just smooth it... then,...open up up the that outer ring to closer match the exhaust gasket and header pipe... (vacuum it out when you're done)...(doing too little is better than overdoing it)...
Go too far, and you might screw something up...

Remember,.. you can take it off,.. you can't put it back...

I did gasket matching, and smoothing on a couple of Mustangs, years ago, and got a small, but noticeable improvement...
On the Savage I did similar work,.. and results aren't really noticeable...
.. but,.. being conservative,.. I'm quite sure I haven't done any harm, ...and it is likely that there is a tiny improvement, if not perceptible...
... or not... ... (but, I know I've done it, and I don't trust letting anyone else try to prove they can do better, by doing more)...

Keep it safe... or you can do more harm than good...
I just suspect, that there's no harm in trying to gently correct the inefficiencies of mass produced casting...

JMHO... I'm no expert.  just a DIY guy...
I do pride myself on not perceiving illusionary performance results...
Don't expect much... if your bike is breathing pretty good, and jetted pretty good,... a little smoothing and porting might allow a bit more potential...

Thanks all.  Just what I needed.