4.8is, stock cats or race? What do you all think?

[vierpunktachtis]

Hey guys

I've been trying to sell my Imolared '05 4.8is for quite some time now and the market for these kind of cars here in Sweden is pretty much dead, so i'm basically having some second thoughts about selling it. The offers i get on the car is so low, i feel it's not even worth selling. Therefore i'm thinking of doing some modifications on it. One of those mods are the exhaust.

Is there any reason to change the stock cats to like 300 cells race?

Someone told me years ago that it could give quite a big HP gain (like 10-15hp). Is there any truth to this, or am i just wasting time and money? I would like to keep the exhaust as much original as possible (the tips on the 4.8is are the greatest). Also, how big weightreduction would this kind of procedure do?

Off topic, other mods i've been thinking about is getting some smoked taillights (blinker and reverselight), white angeleyes, foglights, license plate lights, interior lighting and maybe some AC Schnitzer footrests, handbrake and floor mats.

What do you all think? The car has black leather with graphite metallic trim, high gloss shadowline and panoramic sunroof. Any ideas on other mods?