New to the GM platform 2011 CTS-V A6

I wanting to introduce myself I am a proud owner of a 2011 Cadillac CTS-V A6 Coupe! These cars are awesome looking forward to learning a lot. My car has the following mods. D3 intake , Works 2-in long tube headers 3-in collectors, 3 inch x pipe, reinforced brick, blower isolator upgrade, flex fuel sensor, GP tuning custom camshaft, 90 lb injectors, Dyno tune and and trans tune. Thinking about upgrading the lower pulley or upper pulley next. Looking for some recommendations thanks