One of the things my car failed the SVA was for noise. It recorded 103dBA. Sounds nice, but I need it quieter at least for the re-test.
Where is the best place to get exhaust packing from?

I got some from a nearby motorbike shop...

Otherwise, Car Builder Solutions sell some.

David

Mac#1 usually stock it as well. i think it was £10 a bag last time i saw it.

DIY shop - rockwool a large bale is about £20. If you wrap the perforated centre tube with stainless steel wool (from Milner Off Road) the rockwool shouldn't get blown out too quickly.

CBS were selling off some part kits recently.

From my experience wrap wire wool around the tube as above and then wrap e-glass round this. Not too tight as you want the sound energy to dissapate in the padding. You can use a layer of rock wool/basalt packing in the middle if you have particularly high temps in the can.