Quote:
Originally Posted by KoolBRZ
There is a difference. An open exhaust has a much stronger scavenging effect, especially with the ESC running. The charge can be blown right through with enough overlap at the right time, since the Port Injection is active at low speeds. The OEM header will give you more torque down low, because the back pressure won't allow as much blow-through, but it quickly becomes a restriction above 4000 rpms.
Tunes written for open exhaust and catted headers are different in the AVCS tables. OEM header tunes have much more overlap to take advantage of the back-pressure, while those written for open exhausts have much less Exhaust retard, to prevent blow-through. The difference is audible. You can hear when there is more retard, because it gets much louder.
All my tunes have a bit too much retard for an open exhaust. They are loud when you open them up, but quiet down when just cruising. I usually tune for the limit, when power starts to fall off from over-scavenging. This means they will still perform well in more restrictive exhaust setups.
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thanks for clarification!
I will upload your map once installed
