I hear ya. Im just spoiled and picky. It has to be a 4port 13-B.

 

first rx7 i ever drove was my bud's 79... it was a blast, but i didn't like his clutch setup... it was all stock, and having come from a 85 GMC 3/4 ton conversion van it seemed super fast to me haha... my first 7 was a 87 TII... fell in love with it... then wrecked it, next was a 88 TII pushing 17 psi in 4th gear, definately could fall in love with that! then got a REPU, it had a 76-78 13B, 4 port of course, and that thing was sweet.... till it lost an apex seal 3 days after i got it.... then got a 84 GSL... my 84 had no motor, so i put in a 12A that the shop owner(a rotary shop in the area) told me was a working motor... he couldn't be further from the truth... got that thing installed, and when i did get it running it overheated(radiators fault) and leaked/burned more oil than i could put in it... so that motor was a dud, it was also very sluggish, very tired... so i got my motor i have now... a 85 SE engine... took it apart, ported it, had atkins assemble it, and now its sitting in my car waiting for a friggin oil pressure sender, after fixing the carb, replacing the starter, wiring a new switch in for the fuel pump since the relay didn't work, etc etc... been a lot of work going into this motor just trying to get it running(and i also have about 9 quarts of oil sitting in my driveway, 4.5 from the oil pressure sender being MIA, and 4.5 from the oil level sender being mia(don't have one, tried to plug the holes, unsuccessful).... so yeah, i'm about to be running my first 6 port... and hopefully its pretty sweet lol...i don't think i'd want to go back to a 12A, especially with how easy it was to get the 13B in(initially, the rest is just a side track lol)... no need really, when i can have that 30 extra hp

 

I had a SP 4port 13B in my 81 about 12 years ago. It was nice to make new Mustang GT's go .
I think it would have been hard pressed to get a SP12A to do that..

If my 12A ever goes kaput, I'm pretty sure I'll build a 4port 13B. It might be a while- I've only got 72,000 miles on the original motor..

 

a 12A is great,when you want to build a high HP ,high revving engine.

The biggest problem with the 12a is : Oil passages.They are not able to flow enough when building a high revving engine.The 13B has a great improvement in the passages,and the oil pump is allso way better.

With high i dont mean 9k rpm.When going over 10k ,it is really hard to keep the bearings lubricated,as the passages arent up to it.

Their rotating assembly is much lighter than the 13B`s,but that only helps to some extent.The thing with the 13B is the amount of torque that it has more ,its easier to get the engine revving up quicker if you have more torque. ( i dont mean low down grunt,but torque in general).

If i had to build an engine,i would build a 12A 6 port. I have seen what insane hp numbers they are capable of na.

Its not just the PP 12A that makes hp....

karis