Adding a SRS 2 channel extension or your existing ButtKicker gamer 2 to SRS ShakeKit increase your number of channels from 4 to 5 or 6. This allow the ShakeKit to focus on the subtle suspension, road, g forces effects while the 2ch extension or the BK2 handle the engine and some other effects. This increases your immersion in the game.
This article explains how to add a ButtKicker gamer 2 to your existing ShakeKit
1) Open the ShakeKit box by removing the 4 corner screws
2) Connect the 3.5mm cable of your BK2 to the ORANGE input on the ShakeKit sound card
(you can pass the wire using the round hole in the ShakeKit. Might need to make it a little bigger. If you don't have this hole, you can easily make one using a drill)
3) Set BK2 amp like picture below (Low filter = OFF, High Cut Off Frequency = 120, High Filter = Off). SRS uses our own special low frequency sounds and the BK2 amp should not change it in order to get the best experience.
1) Open SRS app
2) in the SHAKERS tab change profile to "6 speakers -5.1"
3) Optional step: Fine tune. Please read the advanced shake tuning article