98 stock ported heads
 

i would like to know if any body out there has ever had a set of 1998 factory heads ported/polished ? And if so what kind of gains did you get from them ?

I've got a pair of stock ones somewhere in the depths of my garage.... but they're not ported....

To be honest, I'd save for the 99 up PI heads...

About 25 HP
 

There is an article in the January '99 issue of 5.0 about exactly this. It says the HP gain is about 25. The intake flowed 250 cfm @ .45" of valve lift, for a 20% improvement and the exhaust flowed 158 cfm @ .45" of valve lift-12% improvement. The HP gain there was 25. If you use a blower, the gains are more over stock heads. As you can tell, the 99+ heads are superior to the "98-"heads.

The article didn't note how much the porting and new valves cost. If you need more info just let me know.