Radiator cap question

I believe I have a 98 or so jetta radiator in the front of my 67 bug. Im looking to see if any of you guys know if that cap is Pressurized or SEALED. Its the plastic screw in type of radiator cap. Any mechanics out there? HERES A PIC OF MY SETUP

http://www.geocities.com/kewda360/rotary4.jpg

If it's the stock VW Jetta expansion tank & cap (I can't see from picture) it would be a pressurized system @ 19-22 psi. Did you change to earlier style fenders/headlights?

The fenders were bought aftermarket from the last owner, I havent ran the numbers yet. The tag is still on underside.