Stiffness IMO is perfect for split daily/track use.
I almost never miss a shift now, even during a hard corner.
Slight increase to the following sounds:
- Startup sounds bassier, it is interesting lol.
- Subtle gear whine (sounds nice IMO) when accelerating low speed.
- Increased nvh engine vibrations at ~2-3.5k RPM. Thus, highway driving below ~115 km/h is noticeably affected. But above that seems fine. NVH increase is noticeable but IMO it is worth. Note my car has catback (Hks hi power spec l2).
No noticeable change to NVH at idle. Maybe a tiny bit.
NOTE there is an implied intended ORIENTATION to this insert.
You can just slide it in from the front like some people suggest, but it does not fit flush this way.
I think it was intended to be slid in from the rear instead, with the lip at the rear (which may require taking apart the exhaust and maybe even removing the mount itself).
Appears to hold up perfectly fine when slid in from the front :).