Can you return the K&N? If so, do it, thats about the best thing you can do with it. They let WAY too much dirt through and don't really work well. Personally, I feel that dry flow filters are the way to go. If you over oil a Cotton Gauze filter, the oil canbe sukked out of the filter and coat the insides of the piping and the compressor blades. This wieghs down the blades, and makes dirt stick to them, wieghing them down worse. This will cause slower spoolup, poor mileage, high egts, and in extreme cases, turbo failure from unbalanced compressor wheel. I would use an Amsoil nanofiber replacement or some other quality dry element filter. I have an Amsoil for my truck.
As for HP and tq numbers, I don't know. But I can tell you you are going to love that Diablo. They run great, and the 4" will really help the sound out. We just pulled the muffler out of Dinger's LBZ and straigh piped it. Sounds so sweet!