Exhausting issues.....

[Junglehop]

well my exhaust decided to give up on life. i knew the pipe from the backbox up to the silencer tucked in behind the rear wheel was a tad rusty but it has now entirely sheered. Dont think the torrential rain over the weekend helped things!

i cant really afford to get a new fancy sports system despite what it would add in performance. so i have picked up a new secondary silencer (think thats what its called) its the same as the part thats buggered and i have removed this. (but the new one is stainless steel) anyway i have now removed the old one and am left with the following face comming from the backbox:



the face of the part i need to fix is shown below;



now to me it dont look like that will be a suitable fit. Am i correct in thinking that i need to grind down/cut/remove the bit labeled A? this would surely give a flush fit with the newer part. im going to bang on a load of holts firegum exhaust assembly stuff and ive got some holts Gum gum standing by for any gaps..

can anyone offer any assistance as to how this can be done? i want to get the car up and ready for the Lotus festival at Snetterton on Sat and then Supercar sunday on.... erm well sunday...