every now and then I see that 914-6 have 911 Turbo valve covers
even my old Sporto had them
now I wonder why?

what are the pro's and con's ???

The pro is they are stiffer and tend to leak less. The co is they can possibly interfere with inner suspension mounting ears. On my race car the interference made us change from studs to bolts so they would not have to be "lifted" off over the studs.

help cooling as well as seal better...JMO

I believe the only "con" is less stock

I ground off some of the webbing to make the motor clear the suspension better but they definitely leak less. Especially with silicon gaskets.

Just use early 911SC valve covers. Same thick aluminum, close to the same cooling characteristics, and you don't have to modify them (eliminating nearly all the advantages) and they're a LOT cheaper.

The Cap'n

And look period correct

Yeah. These plastic (composite?) 993 lower covers look kinda wimpy at first glance and just for the record, start leaking pretty soon in 914's unless you guard them from the headers.