I think the gen 2 cais he's mentioned is the AS one? It's probably personal preference mate, I'm leaning towards the AS one purely on price, unfortunately I've got to go to DS and collect remap kit and have a DP fitted so I might have my arm twisted by the guys there!
Read through the information that cknott20 has provided in the links above and make your own mind up.
The filter on the DSCI ind kit sits behind the fog light well away from the heat from the block. I've got one on my ST and I love it. It sounds awesome. Have a look in the classifieds on the site. You might get a 2nd hand one for the price of the AS one if that's what you decide to go for.