i'm not sure of the quality of the sil system but i have recently (12 mths ago) purchased a termignoni daytona (48mm) spaghetti system and am more than happy to vouch for the quality of this system. the swingarm needs to be dropped off the lower shock mount to get the rear header on, and the thinwall stainless radiates a LOT of heat onto your left thigh. the inside of the system is all filed for maximum flow, there are no dags or sloppy welds inside or out, infact i would say they are better finished on the inside. my 888 after fitting the system and dyno set up of the pcIII made a healthy 5hp gain from 7500 rpm but it did lose about 2hp from around 3 thru 5000rpm. they are a work of art in my opinion and after looking for one for years i am very satisfied with my choice. hope this info helps.
cheers, paul.