I got signature motoring number from milpas421 ( thanks!) I got mine last week to. Anyway, for further information beside milpas 421! I can guaranteed that this steel metal heat shield is working. I been using it for couple days and I can see what you are saying milpas421. Just want to add it. Signature motoring produces a cold air box that creates a completely sealed using walls of the engine compartment and the hood. Current market only offer a plastic heat shield ( E36 and E46) but simply deflect the direct heat from the side of the engine but allows hot air to circulate around the shield and are far less functional for this reason! oh yah! they are the only E30 heat shield manufacture by the way!
When driving fast on the freeway, your car will not have problem with the air system as the air from outside push the hot air from the engine. But as your car is in lower speed you will lose power especially when your car use high flow air filter like K&N. If you cannot find thread from milpas421, Here is the number you might want to contact: 1-800-526-1744. BMW parts is expensive. $100 heat shield air intake is good for you car maintenance. it is worth it. When you buy high flow air intake system, you might as well get the heat shield as the system is to produce more power. Without the heat shield it willl be less fortunate for your car.