straight pipe and no cat

[blk_shadow]

hey guys just a noob as question..
is there a purpose of having a straight pipe and no cat?
is der any gains?
or its just there for a sound?

straight pipe without cat is used to create better airflow without any restriction, therefore will create extra power. but again, it all depends on what you have done on the intake and header side of thing (or even internals).

its all about balance.