ok maybe i used that as a bit 2 much of a general term,300's to start off with came with nowt,straight dection of pipe & away you go,as the years progressed different specs had them & around 96 onwards it had all the crap stuck to it to make it cleaner,
to make it go better buy an early front pipe & roberts your mothers brother
as jimwillly said its a particle collecter so after a while it will become clogged with soot thus choking the engine