Removing manifold cats...non-reversal cones necessary?

[pupp]

Want to bash out the pre-cats (like a bit of ultra violence ) but, before I do, is it actually necessary to install cones or just a luxury? Anyone had good results without? (anyone had bad for that matter?)

[Nuggs]

I spoke to Paul @ Austec about this before having mine done.

He didn't think it would be necessary on a 400, but suggested a 500 would benefit from (need?) them. Not sure about a 4.5 though...