Most stock engine that are installed in the Fiero have heads that are mass produced
the area just below the valve seat has extra metal for convenience in the manufacturing process
the excess metal can be removed to improve flow on both the intake & exhaust valve area
By progressively increasing the degree of the valve seat angle a more gradual smoother flow takes place !!
A smoother surface is created easing the flow of fuel mix or exhaust gas past the throat area
you must be careful not to weaken the seat area at the throat,less is better for the novice porter

............................Futher performance tips , use care ,easy does it
If you have a multi angle valve job done ,you can improve it by gently sanding to achieve a smoother contour
go with the symetrical 360 degree

each valve throat must be equal ,cut out a round template using the largest hole or 2nd largest in case the largest looks marginal
If you do your own valve job it is easy to open & smooth the throat, easy does it port throat then cut or grind valve seats

there are other methods,, but leave this to the nascar , bonneville & fuel drag guys
TO PORT=if a virgin Go slow remove minimal metal smooooth it out the first time so it will be good for you !! be gentle with me !!
as usuall slams, ,futher information, critique & U suck like a hoover ,all appreciated
I plagerized 50% of this post

clearing my throat.so you read my modification Blathering s
take no more than 80 % of throat when pocket porting or just clearing the throat
at a minimum use duct tape to cover valve seat ,, little nick is a killer

I would do this for the intake valves, but the exhaust valves get beat up quickly. I normally just lap in the exhaust valves.. all the valve job work is short lived for them...

Good point, Stan. The iron 60-degree V6 heads have the intake ports neck down just before the valve, then open up again to match the valve diameter. The transition isn't very graceful. You don't want to completely remove the constriction (it helps control flow through the port). But smoothing out that transition will free up a few ponies.

The exhaust ports also have a "bump" on the sidewall, which is just a leftover from the casting process. You can grind those bumps down to increase exhaust flow. And we all know the 60-degree V6 loves exhaust flow. This is evident in the increased performance from dual-pattern camshafts.