The APR downpipe is a quality bit of kit - expensive yes, but very well made. I had one fitted to my car before I went the IHI route.
It is a bit of a `fiddle`to install on the car - not a 10 minute job!! - but will fit the LCR and once in place it works fine.
You will also need a small `spool piece`to connect to the discharge side of the cat and house the second lambda probe
You will have to fabricate this yourself - Milltek make one specially for the APR pipe, to mate up to their own exhaust system for the LCR - The APR/Milltek combo fits up very nicely and sounds great.
I`m pretty sure the standard cat will not fit with the APR pipe - the pipe comes with its own special, if rather small, cat, and works OK with the standard Ko4 turbo
With uprated software - say APR st 2 - the car will be as good as it can be, bearing in mind the limitations of standard turbo/exhaust manifold