Don't worry Rusty were here for you when you need help! 

 

You're going to need to learn to use those smiley things when you're joking like this :-)

 

But I'm serious !

 

BTW, I'm with Bill on the ports.  I only looked at the inside, since that's where the hole actually is.  I stood a straight edge up on the leading, and trailing edge, and found them to be the same.  I measured the width, which is also the same.  There's certainly a possibility that Mazda made some housings that were different, but I'm only familiar with '86-'95.  

 

Another interesting thing, which I almost hesitate to mention, is that there are folks who are trying to make a small PP in addition to the side ports.  Being small, the overlap can be kept easily in check, and it increases the airflow at high rpms.   Interesting idea, but I'll pass for now :-)

 

That's interesting !!

 

Bill here's a clearer picture. You will notice that neither of the inside edges line up with the ruler but the top one is much lower than the bottom one.

 

The bottom Turbo housing is the housing of choice for the larger PP and in fact they actually remove the insert from the old housing ( if damaged) and put it in a new one if they can't get the housing they want. Could be why they idle so badly, but it certainly breathes better - at the higher RPM.

 

Yes these are older type housings generally used with the 12A end-housings - as I'm using with the single.

 

It's good to know that the newer 88/91 housings all have the same closing timing event. This convinces me that the NA  exhaust timing is the most appropriate for a mild PP.

George ( down under)