I recently replaced the intake bellows obtained from tasca volvo (oem). When it arrived I thought I was getting a rubber one but instead got a volvo hard but thick plastic one. I suppose this is the new replacement part , with which I am quite pleased. The thing is , now I am getting better mileage. The old one "seemed" ok with the exception of a soft spot at the lower end near the throttle body. In fact I repaired it a while back by building it up with gasket silicone..so how is it that I am getting better mileage now? Better air flow?