I took my grp 28 off backorder and ordered an os 28xz.
Horizon has too much history with trying to get products to market and keep pushing back the release date.
From what I have seen the engine only are scheduled to arrive on 4/5. The promo deal with engine and pipe looks like they will not be in till the end of april/early may.

If I see the engine only come into stock on the 5th, I will be surprized.