I have actually kept it in the end Paul, couldn't delete this thread so marked it as sold.
I bought it and then had 2nd thoughts, I wanted a full twin 3 inch system all the way through but wanted to keep the valved boxes. I spoke to a local exhaust builder but it was just going to be a pain in the ass and just as expensive to build one up along with a long wait, testing, etc.
The standard exhaust system is 2 x 2.5'' all the way through
Milltek catback system is 2 x 2.75''
Milltek offer 2 downpipe solutions, as per original spec 2 x 2.75'' downpipes which makes it a 2 x 2.75'' all the way through. They also do new 2 x 3'' downpipes/2nd cat bypass pipes.
The 2.75'' downpipes/cat bypass retail at around £850
The 3'' downpipes/cat bypass retail at around £1350
The 3 inch downpipes are Cerakote coated too.
I figured that as the Milltek catback is 2.75'', by opting for the 3'' downpipes, it would eventually step down into the 2.75'' catback section. I pondered on it for a while as the 3'' downpipes will obviously flow a little better and will rebel heat a bit better so they are the better option, I just think that for what I'm after (Stage 2 750hp levels) then the 2.75'' is sufficient (Considering the cost element too). I think if you are going for Stage 3 higher horsepower numbers, it would be best to get the 3'' downpipes.
As part of the black Friday deal, they was near enough a 30% discount on those prices above, made perfect sense to stick with the Milltek option
) would be a good idea if you were at all concerned