heatshields imho arent worth it, they do look nice, but a large filter with big surface area will suck in enough air for good maf readings, the slightly colder air you gain from the heat shield is then sucked into a furnace of a turbo and heated anyway.... imho cooling after the turbo is the key not prior to, get as much air in as possible to the turbo via the maf readings and the ecu will alter the fuelling for this, cooling the air after the turbo via intercooler, wmi, phenolic spacers is money better spent than a heatshield, afaik the jabba/neuspeed heatshields are circa 60quid, a phenolic type spacer is same price and better spent.
there is a thread somewhere on heatshields and if they are worth it.
thing is again, in the intake manny theres a sensor to mneasure inlet temps, this sensor sits in the manny which gets warm... so trying to cool the air pre turbo when the turbo heats it up tbh is a waste of time, cooling the air post turbo is where to start from for cooler intake temps, colder air = more power ultimatly
id say a good test of a heatshield is... does the shield get hot itself? if not then how much hot air is it dissipating away from the filter, if you want to go this route id recommend spacing the flter closer to the wing where it will be slightly colder.
but tbh, ive never touched my filter and thought feck thats hot... the inlet manifold on the other hand does get hot, well did pre fmic and phenolic spacer.