This may seem like a dumb question, but is there any way I can tell for sure that i have a 6port 13b instead of a 4 port besides actually taking off the intk manifold? Im pretty sure its a 6port because thats what came stock in my car 87na, but the previous owner has an aftermarket intake manifold that looks like its made for a 4 port engine. I tried to take it off and see for myself how many ports there are, but it was too damn tough to get some of the bolts off.

 

Wow that's strange.

I've seen a site detailing how to modify a turbo's intake manifold to line up well with the intake ports on a 6-port, so really the only way to tell is to yank the manifold...

 

The butt dyno may give a clue. If it's a 6-port, power will be quite low below 4k, and will roll in noticably above 4k. If it's a 4-port (or J-spec), power will fall off a little around 6-7k.
I tested this on my 91 n/a by manually operating the 6-ports with a hand pump (MityVac)..