The 4 TBI system has to open all 4 TBIs at the same time and the same angle. There are some lockout produces on the the net on how to lockout the factory 4 carb linkagle to accomplish this.
This direct link system we have developed uses the standard 2 Carb linkage and a linkage between the Primary TBI and the Secondaries. The secondary linkage arm has to be modified with 2 small holes for proper operation and user adjustment to prevent binding. We also recommend a return spring on the secondaries just as an added safety measure and to ensure precise angles are maintained.
Ask for this modification when ordering. This option is an additional $75.00