Well everyone I did some research. Look what I found:

Nutritionally complete, balanced formulas especially designed for oral feeding of children 1-10 years of age. May be used as the sole source of nutrition or as a supplement. PediaSure meets or exceeds 100% of the NAS/NRC RDAs for children 1-6 years of age in 1000 mL (approx. 34 fl oz) and for children 7-10 years of age in 1300 mL (approx. 44 fl oz). PediaSure is ideal for children whose nutrient needs are increased or who may be undernourished due to illness or poor appetite. PediaSure is formulated to support catch-up growth in children with failure to thrive and is well tolerated. "Kid Approved" vanilla, chocolate, strawberry, banana cream, and orange cream flavors encourage compliance (retail and institutional PediaSure). Vanilla is also available with fiber.

i am DEFINETLY going to be swapping out his formula to Pediasure. Not as a single amount of calories, but as a supplement to what he is eating now!

I checked and his formula has only 100 cal per 5oz, whereas this has 237 per 8.. thats a signifigant difference and would help until his eating is more established.