Slow acceleration after intake and exhaust

wstar

A tune never hurts, especially with changes to intake (your gen3) or headers (which you didn't do). Also, sometimes subjective opinions of acceleration are all over the map compared to the real data. Quarter-mile times (same driver/track + DA correction) or a before-/after- dyno sheet would give a more realistic comparison.

You'd be surprised how many psychological factors are working against you on actually "feeling" whether the car accelerates harder or not. Aside from the internal ones, there are at least 3 key external bits of data that can throw you off: (1) The sound of the car changes, and changes differently at different RPMs, so the whole "ramp" of running through the RPMs can sound very different, and seem to sound "slower" or "faster" to you. (2) It's possible for the average acceleration to go up while the delta and delta-delta-acceleration smooths out. You're actually accelerating faster, but you don't feel as much seat-of-the-pants jerk/snap. (3) Likely your intake/exhaust shifted the power curve around. You may actually have traded worse sub-3K performance for better post-3K performance or whatever (which, if you only care about performance, is actually ok. In any track situation you're not going to spend enough time below 3K to care, but the car could actually have less instant acceleration on tap than before when you're at quarter throttle at 2K rpm bopping around around town in traffic).

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