I have been doing alot of flow testing for the last 6 months with both 900 and 1000 cylinder heads. There is alot of stuff about them that shops are not doing and telling people. Alot of shops like to keep there flow #’s secret, and alot just say we have gotten huge flow #’s. (that makes me wonder if they have a flow bench at all).I am the type of person that wants to see flow #’s, not "we are getting massive air flow". One problem out there, that may keep shops from posting flow #’s is that flow benches vary from one to another. If they are not being calibrated regularly, they will vary. Also a superflow bench may show higher #’s than my bench or other benches. But what it all comes down to is the percentage of gain from the stock flow #’s to the finished ported #’s. I have looked at a number of shops port jobs, and ones that have claimed massive air, and most of the shops have not done a complete chamber rework. This is particularly important on a 1000 head because the people over at Polaris, in their infinite wisdom, made the 1000 heads chamber smaller than the 900 head, shrouding the airflow. Without doing the chamber work, your giving up an average of 10 to 12 CFM. On a 2 cylinder motor, that can be at least 2.5 HP plus.
So here are the flow #’S ON MY bench from stock port,(which are pretty good), to ported intake port, to ported intake with full chamber work.

stock at 28 in water
.100 lift– 91 cfm
.150 lift– 133.5 cfm
.200 " — 166 cfm
.250 "— 198 cfm
.300 lift– 230 cfm
.350 " — 258 cfm
.400 " — 271 cfm
.450 " — 280 cfm
.500 lift— 287 cfm

Ported intake
.100 lift — 98 cfm
.150 lift—145 cfm
.200 " —- 179 cfm
.250 " — 211 cfm
.300 " — 243 cfm
.350 " — 272 cfm
.400 " — 294 cfm
.450 " — 305 cfm
.500 lift — 308 cfm

Ported intake with chamber rework
.100 lift — 107 cfm
.150 lift —158.5 cfm
.200 lift —191 cfm
.250 lift —223 cfm
.300 " —-254 cfm
.350 " —-278 cfm
.400 " —-301 cfm
.450 " —-315 cfm
.500 lift —323 cfm

So as you can see, reworking the chambers in the right way, greatly improves
low lift flow up to .300 lift, (better low lift air flow increases both torque and HP) and increases high lift CFM. So look at your ported cylinder heads, and if the chamber is just polished without any other work done to it, you are not getting the massive air flow #’s you thought.

Exhaust flow #’s are very important also, because a weak exhaust will keep a motor from RPM ing and making top end power. Discounting the exhaust, which some shops do, (just polishing and making it look good) will keep it from making those big power #’s, especially on a turbo motor. Exhaust flow is really important on a turbo motor, the more the better!!. The 1000 head has smaller exhaust valves than the 900 head. (about .125 thousands smaller). So porting on the exhaust is very important. I am in the process of getting a few different size exhaust valves made to have a whole thread on Exhaust flow #’s from stock to different oversized valves here in a month or so. This should be of great interest to the turbo guys, because better exhaust means faster it gets on boost, and more manageable power with less boost