Exhaust Silencer for 2.5 V6 Xedos 6?

My exhaust sound way to much and I want it more quiet.. = )

I bought a back box silencer full flow from England but its tooo niose :-/

I change the engine to 2.5L V6 and if I buy the original back exhaust just because i want the exhaust sound more silence, will i loose a lot of power??

Thanks again! = )

[hörnchenmeister]

The exhaust muffler won´t cost power.

The catalysator cost power

hehe Okay! = )