I have recently installed the Forge Diverter Valve (with whatever spring it originally came it, which I think should be green or something) on my 2009 R56 Cooper S with JCW Engine Tuning Kit (Stage 1). According to my mechanic, the installation was straight forward aside from that he had to trim down something in the supplied connect plug wire to make the plug fit since my mechanic said the wire was universal and hence had to make adjustments to make it kit to MINI. I guess this is expected according to what I have read here.

So after some test driving, I found the throttle response is indeed a little bit better, especially on acceleration from stop and up shifts, which makes the power delivery/boost build up more smooth. But from what I have read here, people seemed to have experienced a more dramatic improvement. So maybe it's because I had a Factory JCW Diverter Valve in my car before, so could it be because I should be using the yellow spring instead? My car also have a MINI Mania Intake Filter and an ARC Intercooler, which is stock size but is more efficient. What spring are you guys using? And based on my set up, should I be using the yellow spring instead based on the slight boost increase from the JCW Engine Tuning Kit? I just want to use the appropriate spring for my set up and without affecting the reliability of the engine or the valve. Please advise.

Thanks!

 

I think it's from people exaggerating since they'd feel bad about writing a so-so review for a $230 part!!!

 

I agree 100%. There is so much of that on this forum. I have a heavily modded S after listening to everyone one on here and so many parts did nothing like everyone said. Just look at the posts on boost tubes and noise maker deletes. I have this same part but I did need it after my stock one kept giving way. I didn't notice any gains, other than it was smoother when compared to my stock one which kept giving way. I wouldn’t bother if my car was stock.

 

THIS

 

Thanks for the replies! I guess it make sense that some people tend to exaggerate their feedbacks as the word "difference" is very subjective after all.

So does anyone have advice on what spring I should use given my set up?

 

From what i've learned, the stiffer spring is for tunes that are pushing 19-24psi of boost. I'm not sure the JCW kit for the MCS pushes boost this high. From the very conservative gains you get with the JCW kit, I would say the boost probably never gets this high.

 

stick to the stock spring. you will have issues with the other one causing the turbo to 'stutter' since it isn't making enough boost to properly open the valve.

 

+1. I'm running close to 20 psi with the spring it came with.