Suppression Filter

Wondering if anybody knew where to find an electronic suppression filter for the coil packs? I think they come standard on the TT wiring harness (alrerady asked them.) I have been having problems with my Hitachi coils causing electrical problems in my car when they're under heavy load. Bascially, cause the batt ight to flash alot, and might even be overloading other electical accessories. A tech at the Audi dealer said that these coils were stock on a TT, but were supposed to have a filter to counter act the larger negative spikes created by the Hitachi coils. So if anybody know where to find a filter, or has other help input please let me know.
 
Thanks