You want a big bore LMS header and R3T single pipe then.
Les @ozrider is only doing single pipe versions for the R3T now. @Kevin frazier can vouch for them as do many others on their Roadsters too.
I have a set of Ozrider's LMS big bore 2" headers with a single pipe for a Rocket III Touring. I didn't fit them before I wrote my R3T off. They were on another blokes bike foe a month or two before he sold it.
And of course to go with it I have brand new big K&Ns or a RamAir to suit with a used Dynojet Power Commander V / Auto tune and a @DEcosse 'walk up' keyless ignition!
This is photo when I purchased and they are still in their parcels.