To get a torque converter with a mid range (mid 3000's) stall and also have a high shift extension (upper 5000's)?

Or is it not physically possible?

 

I believe a lower STR one may let you slide up a little higher,
but that degree of difference I think is a bit much. You might
want to talk to 1jfuddle about their custom capabilities, see if
you can get in on the (mumble mumble).com GP. John seems
to be able to explain the tradeoffs and predict characteristics
really well.

 

If by mid-3000 you mean 3500 stall, the yes. Most 3500 series converters have a shift extension of about 5200, with a 2.0-2.2 STR. My old Vig3200 had a shift extension of 5200. My current test model B&M Holeshot 2400, with a 2.0 STR, has a shift extension of 4500. All you have to do is settle for a lower STR (better efficiency). If you want a hard hitting 3500 converter (2.5 STR) with a high shift extension (6000), you will be hard pressed for that.