The differemce between the SLP and the Thrashe/MSP CAI are that the SLP has a 7 inch cone, while the Thrasher/MSP have a 9 inch cone. The SLP is more along the lines of a less restrictive factory box, while the Thrasher/MSP relocate the PCM and definitely allow for more air to come through. IMHO the Thrasher/MSP are the best pre-fab ones out there. And I have used the K&N Drop-in and there is a huge difference between the two. Just listen to the whine when you step on it with a CAI...