I spoke to an industry person who is an expert on such matters as this, a person I greatly respect whose knowledge exceeds my own. He in essence agrees with Dimman:
Quote:
Originally Posted by Dimman
It isn't so much that there is a horrible dip, but that the motor manages to create a LOT of torque in the 2500-3200 rpm range. (Name another 2.0L NA motor that makes ~150 lb-ft @ 3000 rpm...)
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It's not so much a "torque dip" as it is a "torque bump" under 3500rpm. This is caused by aggressive scavenging from high overlap--lots of intake and exhaust cam phasing combined with the characteristics of the manifolds.
it would take, at minimum, changes in the intake and exhaust system to add torque around 4000rpm. Like any other resonance tuning, when you improve one area there's a chance you will hurt another.
It seems unlikely that you could just reflash the ECU on a stock car with merely a catback and "get rid of" that dip without lowering torque somewhere else. There are a lot of engines with conventional port injection and cam phasers that have a similar dip.