What mid box to reduce noise?

[antnicuk]

I am currently running a universal 2.5 inch mid box and I\'m at 103 db at 4500, I now have a slightly bigger turbo and want to increase the down pipe to 3 inch but will need to get a pretty good mid box to keep the noise down. Any suggestions for one that wont reduce power ?

Are these universal sports cats any good?

I have loads of room so size or shape isnt a problem.