I think you should check with Mercury to be sure you can run the silent choice ,I ,m pretty sure there is a service bulletin that came out ,and said that there can not be used on a 525EFI because of reversion issues .

Almost every ZR I've seen doesn't use "Silent Choice" but they're actually running the Teague switchable mufflers. Either way, don't run with them on.

Through-prop can be used up to 2,500 rpm. I only use mine at idle except for one time when a local water pig was giving me a hard time and ordered me to plane out so he could hear how loud my boat was. I was tempted to trip the lanyard and tell him it wouldn't start and could he please tow me in :). Instead I slowly planed out in quiet mode and he was clueless that the exhaust wasn't coming out the tips. He said it was still too loud and I was lucky that he didn't have his decibel meter. Yeah, right. He gave me a hard time because my passenger was wearing a lifeline vest. Not CG approved he said. I tld him it was a $300 racing vest. He still had his panties in a bunch so I pointed out that we aren't even required to wear vests. He was preparing to write me a ticket for illegal vest back at the ramp when I pulled out the neoprenes. That pissed him off so he wrote me a ticket because my registration numbers weren't in 100% compliance. What a jerk. Anyway, Q&Q is fine at idle and very low speeds on a 525!