Actually, I've heard a pair of Audiobahn 10"s, (yes, I said the "evil bahn") subs in a bandpass box that was made for 2 Jensen 10"s, (the prefab one). The Audiobahns absolutley slamed in them, and the SQ was above decent. Maybe that's the only way to get bahn to sound good, put them in a shitty prefab bandpass box. But I agree with most everyone else on here, Type Rs prolly won't sound that good in bandpass, unless it is made perfectly. In the long run, you'll probably save going w/ a ported enclosure. And if done right, the ported will be louder than the bandpass, and will also be cleaner.