[Roadsters] Exhaust pipe diameter

[JohnnyRoadster]

Getting new exhaust this week.  I already replaced the manifold with a header.
So just getting new from there back.

Questions,

Shop is recommending moving muffler back towards the axle, instead of under
drivers seat.  Is that OK?

Is a resonator actually needed?

It looks like the pipe on there now is 1.5" diameter.  I asked about going to
1 3/4", and shop said no problem.  Does 1 3/4 fit thru the frame holes without
any mods?

Thanks in advance for replies.

I am off to clean the oil leak residue, since the shop won't weld with the
'fire hazard'

John