OK does the exhaust need to have all it's joints fully gas tight?? does it need to have all joints clamped??
My system seems to fit well together 4> 2 >1 with nice fitting slip joints and a bolt on gsxr silencer. The bracket for the silencer is the only thing stopping all the joints from slipping rearwards. It is more than up to the job IMHO and i'd like to keep the clean lines of no clamps if possible.
I'll try and post piccies later as camera is flat.

My 4-2-1 has springs which hold in under tension. After a couple of heat / cool cycles it is as good as welded tight!

HTH

Mike

That's how my Cat exhaust went together but I did use CLEAR silicone sealant on the pipes to get a gas tight fit. The pigment in coloured sealant will burn but as there is none in clear it will not.

Ive used clear silicon to seal my stainless system too. Needed a clamp though. Mikalor clamps are rather good looking imho.
For SVA you have to take care with the end of the stud. I fitted bolt cover.