Am I thinking of mucking it up?

Currently chatting to Gary at Track Dog Racing about a Rotrex Kit... Watch this space.

Lol, they are very sexy.

We dont seem to hear much about the MP62 Supercharger these days, I used to have one in a Merlot, It had about 220 Hp,
What I found out with it was the fact that on the Mazda throttle body it was restricted on the inlet side, I was looking at a GM throttle body for the inlet which would have allowed a lot more air in.
I still have a Vauxhall Throttle body conversion that I was playing with in the shed.
Unfortunately the interior of the intake pipe failed and got sucked through the works Snapped the belt and chewed up its guts.
End of Idea for the mods !!!

The answer is:
Neither
One but not the other
Both

Its depends on the application and who you ask.

I do a country road 'hill climb' now and then. it's about a 4 minute climb up maybe 500 meters elevation, lots of curves. It's really close to my home. And empty most nights.

I'm an untrained driver. Done the climb in the turbo several times and the ITB car just once. I time the runs. turbo runs about 180HP without control and 220HP with boost control. ITB is about 120HP. all this at the wheels.

The ITB car's last (and so far only) run was 10 seconds faster than the turbo, because I don't really boost much in corners but with the response of the ITBs I'm way more focused with the throttle.

I think with boost control on, and the added 40-50HP, I'd make it up on the straights without becoming braver in the corners. And ultimately the turbo would be the faster car, if I were to be a better boosty boy in the corners.

The thinking and measuring and thinking leads me towards the realisation that the ultimate MX5 hillclimber would be with a swapped honda NA engine - either the V6 or K24. K24 with ITBs would be the dream car heh.

back to your Q. BOV and Boost Control ?

Boost control - DEFO YES

Yes, you'll want the boost control so you can get more boost further down the rev range. There's also the total power output that increases.. as per my numbers. Look at the pierberg VAG controllers they're cheap and plentiful.

BOV - .. PROBABLY YES

I'm not absolutely sure but I think the BOV can improve response on fast shifts because the turbo keeps spinning without backwash. Am I that fast at shifting ? doubt it. I run a (silly) recirculating setup on the turbo car because I can.

also, stu stu!

Boost Control - yes - as Atlex says it can help boost come on board more smoothly and further down the rev range. If you have a reasonable ECU you can also do boost vs. speed which can help immensely with traction, boost by gear (again, traction) and generally manipulate the amount of power in a way you can't without. You can get cheap MAC solenoids which are what most of the aftermarket boost controllers use, or use a Pierburg which a lot of German cars have as standard.

BOV - yes, but recirculating not vent to air. It's supposed to prevent turbo stall when the throttle closes, also prevents your car sounding like something from the cover of max power in the 90s... For moderate boost levels Bosch ones are fitted to a lot of VAG cars and are cheap. I probably have one in the shed somewhere if you want one for the cost of postage.

controller fits between the wastegate actuator and a source of boost pressure (the closer to the turbo, the better)

keeping the wastegate closed earlier lets the you build boost faster.

the wastegate is opened by air pressure. the controller just reduces that airpressure either dumbly (air bleed or 'resistance' valve) or some electronically controlled some solenoid limiting how much pressure gets through - you can get your ECU to do it or an ECB device which manages the signalling..