No they dont run very well without them, you can fool the ecu with a resistor but its not a good thing to do. Im going down the road you originally were, to start with im lopping of the factory mufflers and just fixing on the shorty reverse megaphones, but im trying a set of triumph headers, and that failing having some made up. Can i ask why you stopped with that one? It will be a bit of a job to tune the bike (power commander, or maybe a wiseco fuel controller among other things) back to all work like out of the box (i wont settle for less than a complete, bug free no hassle perfectly working setup) but i think its a first step to some better power, just want to avoid moving it too high in the rev range.When the crossover pipe goes i will weld an 02 sensor bung into the new header pipe and fit it into the left side.
Glad to see your pipes have worked out, bit of a shame that drilling out the baffles didnt for you, but the stock sausages look a bit naff anyhow.
Cool on the front cowling, cant wait to see how it looks! Yep, there are folks out there in the u-s-of-a bobbing, chopping and also cafe-ing sportsters. The spare cowl i have here came off a v-rod would you believe. No accounting for taste... ah well.