I was installing my headers tonight and noticed that the stock gaskets and PPE headers match and are larger the the cylinder head exhaust ports.
I took my subframe out since I'm doing my suspension work at the same time and it would be pretty easy to port the heads to gasket match with all that room. I'm not sure what if any the gains would be. I did a search and was surprised that I couldn't find anything on this topic.
I'm not saying I am going to do this but has anyone gasket matched the exhaust ports on the cylinder heads?

 

You will have to pull the heads off. But I think the results will be positive.

 

To port match the ends of the exhaust ports there is no need to pull the heads as long as you know how to keep debris out of the ports. I'm not talking about reshaping the ports, bowls and dividers.... Just gasket matching. I'm not sure I'll do this, I would need to know how much material is there and if there is a gain to be made.
I just find it interesting that I couldn't find any mention of this in previous threads.

 

I have port matched a bunch of ford push rod 5.0 heads back in the day. You just really need to know how much material you have to work with. You could just roll the edge to match the headers and not take away much material. I don't think you would see much gains. Maybe 10hp. You could also take away power by making the exhaust port bigger you would lower the exhaust velocity out of the head. Maybe someone will chime in that has attempted.

 

That's pretty much my thoughts. I was thinking of just rolling out the edges to match the gaskets but I don't have any feedback/results to push me towards doing the work. I've done so much porting in my life that it won't hurt to never see another shaving, clean a clogged bit or blow up another grinder
I'm still in warranty so I'm going to save this for another time. I'm bolting the headers on today.
I still think it is a good topic of discussion.

 

There may be a good reason to leave the ports unmatched - without knowing if they're using the size difference to control reversion, you could make things a lot worse. On the other hand the Japanese approach to port design tends to favor smallish exhaust ports. So it may improve things too. Hard to say what will happen without trying, but it would really be an expensive proposition if you found you got a reversion problem after port matching. I'd want to take the heads off and see what they really did with the ports before putting a cutter in them.

Toyota usually puts a lot of meat in their ports, so it's unlikely there will be a problem opening them up a millimeter or two. I took 2.5mm out of the intakes on a NA Supra head without issues, so I'd be surprised if Yamaha put thin ports in the heads on the 2UR-GSE.