Anyone know of any good 4.5" muffler inserts?

[sublime_whatigo]

A local car I do a lot of work for wants to quiet down his exhaust a little. He has 2 4.5" tips on some glass pack style mufflers. Ive heard of these things flying out going down the road and have never messed with them. Some good brands to check out would be helpful. Thanks.

[Amphiron]

Tell him to get rid of the dumb ass fart cans.