Re: Greetings from Colorado
Unless you have your heart set on using 415 chain, you can go to Ace Hardware and get #41, which is interchangable with the kit supplied 415. Grainger also carries #41.
As for running open or loud exhaust, you're not doing your engine or the hobby any favors. We're on thin ice here in Colorado with our bikes and running without an end cap or baffles is just asking for trouble. Keep it muffled. The power increase is negligible and is mostly in your head. ie: More noise= more power.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"