How easy is it to do? Just wondering if it was something i could do with minimal tools and experience or would I be better to take it to a garage or muffler specialist?
Not what I would call 'easy'.
This video on changing your downpipe is the one I used when putting in my catless downpipe.
Even though you're not doing that it will give you plenty of guidance on what your thinking of doing.
Just make sure you do it when there is somewhere nearby that has the studs and nuts in stock in case one rounds off or breaks and needs replacing.
You've already got a custom catback exhaust haven't you?
