Am welding 3" SS ( 304 ) 1/16 wall tube for an exhaust system .

Tigged one joint , but the inside of weld is a mess. Lots of fluffy blobs.
Tried lowering heat, similar result.

Bought some ss mig wire, but forgot contact tips, so have not tried the mig yet.

Alot of guys are doing there own exhausts. Do they all purge the inside of pipe to get a decent finish ?

The stilagtites I'm getting would seriously effect the exhuast flow !

Any opinions welcome.