IMHO, if you're still running stock head unit, a graphic eq will sort it, but your masking an inherent rubbish source....
Kinda like using a plaster to repair a leaking pipe....
The Hertz & MTX is a great start, but again drawing to other comparisons in performance - it's like expecting a major boost in power from just a backbox... when you really need a full decat & decent induction..... you've just sorted the backbox.....
Dan
