I can get this size over here for $159. Looks exactly the same. I worked out that the450x300 and the 550x230 have the same frontal area more or less. the fact that the 550x230 was 65mm as opposed to 76mm then it might have less lag and let more air through to radiator. Both have much greater capacity than the ones from the uk and this still fits in basically the same place.
I have a bigger core put in the standard tanks in my 300tdi.( I reamed out the inlet and outlets and flowed them at the same time). When I got this done they said it should definitely use plate as it was able to withstand a knock or two and showed me one out of a crashed car that was still good a gold. I found this advice to be well worth taking as not long ago I took a branch to front of my car cracking the grille and puncturing the radiator but leaving only a scratch on the intercooler. The standard one would have been stuffed as it was another branch the killed it in the first place.

