2D6 metabolizes tramadol into O-desmethyltramadol. GFJ does not inhibit this as far as I can tell. 3A4 is responsible for metabolizing tramadol into N-desmethyltramadol which is not active, so perhaps it may provide some potentiation via GFJ (I have read anectodal reports as saying so) but not convinced how much it would be worth it unless you have low tolerance.