I think the theoretical limit is 104MPH. On a level road, the top speed is limited by rev limiter protecting the engine from excessive RPM due to the gear and pulley ratios, not by torque or HP.
Pipes and AC can get you to the max speed sooner, but you won't be any faster.
I don't know what the topend on my 883 is. Course it hasn't been an 883 in nearly 14 years. Converted to 1200 with a lot of engine work mine has gotten upwards of 130mph, if you care to believe that bicycle speedo that jumps 10 to 15 mph then the speed wobble hit and I quit lookin at the speedo. She goes fast enough, I don't need an exact number to be happy.
IMO the best way to judge how fast a stockish 883 is in 1/8 mile and 1/4 mile 0-70. That was why I started lookin at getting a sporty to begin with. Went to the drags and saw sportsters kickin the heck outta V-Rod destroyers. 90 % started as 883's then converted. I rode home on my Road King and felt like I was piloting a winnebago. lol Wish I coulda kept both.
108 MPH on my '04 while going from Sedona to PHX yesterday...shocked the hell out of a pack of BTs I flew past on the southbound 17...this was with my fully stuffed T-bag occupying the passenger seat, another T-bag strapped to the handlebars and a bazillion bugs stuck to her.