This paper explores the consistency strength of The Proper Forcing Axiom (PFA) and the theory (T) which involves a variation of the Viale-Weiß guessing hull principle. We show that (T) is consistent relative to a supercompact cardinal. The main result of the paper is Theorem 0.2, which implies that the theory "AD R + Θ is regular" is consistent relative to (T) and to PFA. This improves significantly the previous known best lower-bound for consistency strength for (T) and PFA, which is roughly "AD R + DC".satisfying the hypothesis of the previous sentence is called κ-approximated by X. So a hull X is κ-guessing if whenever a ∈ X and whenever b ⊆ a is κ-approximated by X, then b is X-guessed.In this paper, we study the strength of the following theories • The Proper Forcing Axiom (PFA);• (T): there is a cardinal λ ≥ 2 ℵ 2 such that the set {X ≺ (H λ ++ , ∈) | |X| = ℵ 2 , X ω ⊆ X, ω 2 ⊂ X, and X is ω 2 -guessing } is stationary.Guessing models in [26] are ω 1 -guessing in the above notations. It's not clear that the theory (T) is consistent with PFA (in contrast to Viale-Weiß principle ISP(ω 2 ), which asserts the existence of stationary many ω 1 -guessing models of size ℵ 1 of H λ for all sufficiently large λ). However, it's possible that (T) is a consequence of or at least consistent with a higher analog of PFA.The outline of the paper is as follows. In section 1, we review some AD + facts that we'll be using in this paper. In section 2, using a Mitchell-style forcing, we prove Theorem 0.1. Con(ZFC + there is a supercompact cardinal) ⇒ Con(T).Of course, it is well-known that PFA is consistent relative to the existence of a supercompact cardinal. Theorem 0.4 suggests that it's reasonable to expect PFA and (T) are equiconsistent.Recall, for an infinite cardinal λ, the principle λ asserts the existence of a sequence C α | α < λ + such that for each α < λ + ,