A 2117 is way too stiff for a 45# bow.I use 1916's and 2014's off my 47# longbow with great results.And if ya want to shoot carbons,Carbon Express is coming out with a Heritage 90 which should spine perfectly for that weight.I can use my Heritage 150's but I have to put some weight up front to soften them up enough(which really isn't a bad thing anyway)