I am going to install 6mm spacers in my Boxster MY99 (manual transmission) with SportClassic II wheels
Front: 7,5 J x 18 ET 50 
Rear: 9 J x 18 ET 52 
Two questions: 
1. Recommended by Porsche is 5mm...... Can I try 6mm? no problem?
2. Will I need longer bolts or just standard bolts?
   
 
 
 
Regards.