The coil bowing towards the front of the truck is indicative of not enough castor. HOWEVER, thats not always the case. You always want to make sure the alignment is correct. If the coils are bowing but the alignment is where it should be, its not going to affect performance and its just something to live with. Think about the spring in a Bic pen, put compression on it between your fingers and it will bow. Coil manufacturers do there best to design coils that bow as little as possible but its pretty much inevitable to some degree. Sometimes rotating the coil may help a little, sometimes it will make it worse.