what will i notice?

That doesn't mean it is a bad buy. The only knock against the stock valve is that it won't hold up to additional boost after you chip your car. The Bailey will be more durable, but it won't make your car perform differently, if the stock one is in good condition.

There is great diverter valve test info in the linked webpage. Click the link.<ul><li><a href="http://dv.mistertam.com/">Diverter Valve Face Off</a></li></ul>