I havent seen any discussion about the inlet butterfly and assume most people arnt using them....

but check this out

Because mine has the autronic, we fiddled around with the same stuff. No charts to show you.
But that does say the same thing we found. Hooking them up properly has a low speed improvement you can't deny..

Of course, the chart there doesn't show what 'removed' butterflies' does, I think you'd see an improvement up top.. but the same power difference below 4000rpm.

Remember this is a 4th gear dyno chart... You lose this low rpm power on every gear.