I have a full 4" MBRP on mine also. The only issues I had were it is a very tight fit between the downpipe and the oil rail as it comes off of the wastegate housing and begins to turn down. Also, it is a tight fit at the first cross member in the frame at the transmission. This may be a MBRP thing, it may be an installation thing (me). I had difficulty lining everything up straight and clearing these two areas. Other manufactures may have a better fit.