Thing is bud I already paid a good whack to get this system made up

live and learn.
So was wanting to do it on the cheap.
I can buy a metre length of stainless, 90degree bend,3bolt flange and gasket all for under £50.
This is how it is at the mo.

So I was thinking where the top arrow is is where the new manifold should finish and where the bottom arrow is I could just grind off and fit new 2.5" bore.
Dose that look doable.