[urq] hesitation at higher RPM & boost

[i.rautenberg at waratap.com]

IME and based on what has been said, I also believe that spark is the  
issue.  Are you running the proper plugs?  Haven't used a Jacobs  
ignition in a VERY long time.  Currently running an MSD Blaster.  You  
may want to check voltage to see if you're not only supplying enough  
to the plugs, but also to the coil itself.  Pressurized engines are  
much more finicky to inadequate spark voltage IME.

Also, I'd do another test:  have the boost dialed back to 12 psi and  
remove the fuel pump jumper.  That way if you get the 4k cutout  
(depending on what the TAP computer mod is), then you'll have a better  
idea that something else is out of whack (like air intake temp sensor  
readings, etc.)

Good Luck.

Ingo