The TD04L differs from the standard TD04 only in that its exducer is about 0.15-inch larger in diameter. A compressor and turbine wheel have two basic diameter measurements, the inducer -- where air goes in -- and the exducer -- where air goes out. In an exhaust turbine wheel, air goes in through the larger diameter portion and spins out through the smaller diameter. An compressor wheel is the other way around. The TD04L uses a turbine wheel with a 1.86-inch inducer and a 1.62-inch exducer, up from the TD04's 1.57-inch exducer.