blower output

We're running a 540 KB Olds on the dyno with a 14-71 hi helix retro@34%over. It makes 20 psi @5000rpm and flatlines all the way to 6200rpm. We had other problems and didn't get any other data. This boost seems low. I restripped it about 10 runs ago. It made 29lbs on a 526 bbc at 7200rpm and the same overdrive. It's a mid 1990's Kuhl blower with the big top inlet and retro/pie outlet.
When we twist the engine higher will the boost come up? or is this on track for an old blower. I'm willing to strip it again but I don't plan on it every ten runs. I was thinking about throwing new teflon in it at least.
Thanks, Mike

 

i am by far no blower expert, but that sounds a little low. should come up though when you crank up the motor higher. we have a 1997 SSI "B" rotor blower on a 540" hemi at 39% over that made 44 lbs. it is not a retro, and has 9.5 top opening and small outlet.