Top tip #1: bead the pipe otherwise boost will blow it away, most engineering/exhuast places will have beading tools which they will let you use for a cheap price. WARNING though, some of them ebay kits use alluminium (well most), what we found out was, if the bead is close to the mandrel bends it can split the pipe open. However custom piping is not expensive, could get a custom pipe work setup for £150ish made using stainless steel.
The beading tools are constantly on sale on ebay, but they do come with a price tag £120~150, unless you will use it regularly, then heading to an engineering place may be more cost effective
Top tip #2: Go buy some hair spray, spray on pipe and inside silicone, leave 30seconds, then put together, the hairspray will make a rough grippy surface which will hold better than "smooth slippery silicone+bare metal". A lot of guys do this as insurance, plus the hairspray will not damage your engine in anyway.
