Alta IMHO is a good product, but doesnt have an internal rampipe with 360 deg rolled edge machined from solid, nor a second heatshield skin, plus its (heavy) mild steel rather than anodised alloy, + Alta takes much longer to fit or remove for 'discrete servicing'. Plus the hose is too large at the TB end plus the Alta hose has no step inside which it needs to cancel the step on the TB rim.
We flow benched one against the (very similar) GTT Ram kit we do for the Renault a long long time ago. The GTT was around 15 -20% up on CFM . Take the GTT ram pipe off our kit and the flows very similar... The GTT Rampipe design makes all the difference. Our kit is available in a 'new' blue or black now at no extra cost. Red /Yellow etc £10+vat extra.
Best Regards Roland GTT
