What do you mean by 'low revs'? Try and make sure your dealer has given the ECU the latest reflash - M3HUS05Z or even the previous one which ended in 3z (Part No Y0152.1AM) Don't be surprised if you get shrugged shoulders and blank looks when you ask

(unless you use a good dealer like Mchr HD

)
As for silencers, there's a few on the market. If I was you, get in touch with Tubbs (a frequent visitor to this Parish) and he'll modify your standard one and give it a weather proof coating. I stupidly fitted a Remus and when a weld failed on it allowing the baffle to fly out of the tail pipe, the best I could get was an opportunity to BUY a new one. There must be a small print clause in the Remus warranty that I didn't see saying something along the lines of 'If our product fails, then tough shit, you shouldn't have been dim enough to buy one'

My advice is, avoid their products if that's the contempt they show for their customers
