Wasted your $$ on the PI if you already have the Euro intake. You're not gonna notice any gains with the PI over the Euro.
Heck, a lot of us got the Euro intake to replace our standard 2-part intakes as a less expensive alternative to the PI...
Plus now you're gonna have to hack out the carbon filter in the rear box of the standard intake just to realize the same flow you already had with your Euro
And yes both the upper & lower snorkel AND a cover for your Euro airbox are already available in carbon fiber (I have all installed on my 328ix).
If you insist on going with the PI, no need to buy a standard airbox, you should have no problems finding someone that will trade you their standard airbox for your Euro version - I traded my standard airbox to a member in Europe that ran into the very same problem as you.