BAM dump valve noise change.

Blue is far to hard. It will cause turbo stalling which can kill it.

Yellow I softest, then green, blue, then red.

Green will be sufficient, thats what I run

Pretty sure green is softest. 

https://www.forgemotorsport.co.uk/Valve_Spring_Tuning_Kit--product--826.html

Roach is right

Here is the psi ratings for the colours

Green - 5-15 PSI. Yellow - 15-23 PSI. Blue - 23-30 PSI. Red - 30 + PSI.

I've just put the phone down to Forge and I have a FMDV006 re-circulation valve on mine apparently and they are happy that a blue valve spring (which was always supplied with this valve as standard) is okay which surprises me give what you guys say and what this says ;
 https://www.forgemotorsport.co.uk/Uprated_Dump_Valve_Spring_Single--product--825.html

The guy says he thinks it sounds like a leak on the solenoid pipe side of things or the valve (N249) itself.

Any comments ?

As said already.

My guess is you either have a boost/vac leak, or your valve is sticking/too strong a spring.

I've asked these questions before.

Is your valve correctly lubed up?
Is it holding vacuum?
Do you have a leak somewhere?

Looking up your valve, it seems they only supply a blue and yellow spring… So maybe the spring is correct for that type of valve?

Blue is far to hard despite what forge say.

There is no way that amount of boost is being produced consistently enough to operate that spring effectively.

It may peak at 23psi but it's going to try to stall the turbo and by the sounds of it you are lucky to of just had a boost leak elsewhere rather than knackering the turbo bearings

Blues and reds are usually associated with hi pressure systems in jap cars

Okay, I'll order a kit which is 1 of each colour, how can I tell if it is correct and doing what it should be when it should be?

Rolling road at a guess 

Hold fire, I may have a green one in the shed I can send you if you  like?

It'll work fine with your setup.

Roach said

Hold fire, I may have a green one in the shed I can send you if you  like?

It'll work fine with your setup.

Cheers dude but I've just ordered a service kit and a spring kit  
Oh well at least I'll know the piston and O rings will be good for a while and I'll be able to do someone a favour with the springs I don't need.
Thanks for the offer though.

Green will work (was about to offer mine as well) but best bet will be Yellow.

Try both see which drives better