DesignTek Stage 1 Exhaust question

[shlim8]

Hi,

I've been bitten by the mod bug.... looking at DesignTek Stage 1 exhaust for my 2001 2.7 boxster Tip.

It comes with the 2 equal length headers, 2 sports cat and the muffler box. Claims an improvement hp of 18-22hp (??!)

Questions I have:
1. I thought the 2001 2.7l boxster comes with 4 cats (ie 2 secondary cats) so what happens if I delete 2 ? Are there sensors on all 4 cats ? Hence may CEL on me ?

2. Anyone using the DesignTek Stage 1 exhaust ? How's the sound ? I'm looking for something not too loud

3. Is it possible that a exhaust system alone can free up 18-22hp ? (my previous cars are more "conventional" cars like Scirocco, WRX etc and an exhaust alone would probably free up only 5 hp (if not reduce hp instead !)

Anyone ??