What the best dump valve for 350bhp? but reliable?

Forge 006

Yup - another vote for the Forge DV006

I fitted a "MK I" version (blue plastic piston) to my Sprinty soon after I bought it in 2003. I did well over 150,000 miles with it fitted and only ever pulled it apart once for cleaning

When I finally replaced it, it looked terrible - all the stainless screws had corroded into the alloy body and it was badly scuffed where it had been rubbing on the battery tray. However, it still worked fine - I sent it to Forge just in case they could learn anything from it.

The "MK II" versions have an aluminium piston, so should be even more reliable

Or forge RS if you like to adjust stuff
Adjustable and holds high boost very well..

Is there any need for a bigger dump valve then 25mm,maybe 50mm on high boost or high power applications (400-500bhp)?

I have a blitz unit and it's been going strong for years also it's adjustable so loads of noise or none at all.

No - just make sure the orientation is correct and that you're using the lightest spring

Another vote for forge from me - straight replacement for the standard valve too, no flanges needed.

And Guys, what do You think about the newest version, the DV008?

forge 006 has done me well at 340 HP.. no problems as yet, mine is recirculating as not to give the woosh sound to open air.

Nobody can explain me the difference?