you will be pushing the absolute limits of the internals. I know of a guy at MTU who is running 15 psi off of a turbo but has a conservative tune! you may be able to do it. he is at 250 whp and 230 wtq.
where is your power at now, and where would you like it to be? if you want anything over 250whp i would say DEFINITELY start thinking about a new motor, or a badass internal build. especially if this is your DD, you can't gamble (unless you've got some cash saved up).
imho, anything over 220whp/200wtq on our cars is dancing with the devil.
looking at your mods, i would hesitate to put a smaller pulley on. that is unless of course you have the money saved up for a new motor and just feel like blowing something up.
on a side note, welcome to the site. you and i aren't too far away, i hope to see you on the road sometime.
the only thing that may cause pain for you if you push to 15 is the connecting rods. it's the only thing that's handicapping a Zetec change them to a higher quality ones and you can push it to 15 also make sure to get the ARP stud bolts