[niky]

On the contrary, I've seen many dynos showing a loss in low-end (and sometimes midrange and even top-end) power with a big exhaust. It's all relative. Some engines (particularly Hondas) seem to never have enough exhaust... and you can go pretty big with them with no losses at all.

But others have such restrictive exhaust ports and are so sensitive to exhaust scavenging that going just a little too aggressive can lose you power. Just because some motors can take way more doesn't mean all of them can.

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I've experimented with so many different iterations of airbox and pipe on my car that I can safely say that it still does matter, even at part throttle cruising. What we finally settled on was a hybrid WAI, with the filter all the way behind the headlight, attached to the MAF with a stock diameter tube to promote laminar flow at the sensor mount, followed by another smooth, stock diameter tube going to the throttle body. This produces the best power at all rpms, colder running on the highway, and no danger of water ingestion as with a full-on CAI.

Likely a stepped diameter tube would do better, but this would require a MAP conversion, which is too involved a project for me to consider on a daily driven car.