I set the the 6 sets of packings in a different orientation to accept high pressure and vacuum. Then using a variable speed pulley I’m able to mechanically tune the rpm, it’s a fine line when tuning the rpm! A lot depends on how experienced the tech is running the machine. If the tech does not care about quality and just wants to get done with his/her shift. Then it’s not worth having the pump recover 2x as fast. You really need to keep an eye on the honeypot. Otherwise it will boil your shatter and pour like crap.
You can make a t-91 recover just as fast a stock T-291 with these mods. You just don’t want to run Corken’s or blackmers at 100%. You’ll start melting the piston rings and packings fairly quick.