Yeah it really depends on what u are after, they are both very similar in terms of power gains. I've gone with the stillen an berk HFCs. Go on YouTube an listen to Semtex videos when he just had these installed. He got some pretty damn good gains with this combo, so did a few more ppl.
The fi exhaust makes the car look tuned from behind cos they are more visible, took me a while to get used to them but I reckon they look good now hehe I saw bezzitas car a week ago and it looked Damn good very hot from behind.
just be prepared though, you will get massive gains with high flow cats but these increase the noise quite a bit. This worried me a little but then I came to the conclusion that it's a sports car lol as long as there isn't any drone, I'm happy
from what I've read about my combo there isn't any drone. I'll let u know definately in a few days