here are the parts i used on my downpipe. theres one flexi, and one spring type bolt joint. (one on the right top.) i got two flexible joints on my downpipe, because after downpipe, the exhaust is firmly bolted on my chassis via these rubber bushes. those flexible joints allow enough play on exhaust, but its still very firmly in place. this is how it looks like from under

those parts cost me about 120 euros. then just some welding and fitting. the downpipe would look much more nice, but i had to make haste to get the car done by trackdays.