I use the same Coopers IPA kit, and add a 3lb bag light dry malt extract, 1 lb corn sugar, and an extra 2 ounces of hops, half in boil, half at very end.
When I used 2lbs corn sugar and 2 lbs LDME I noticed the flavor thinning, but with just 1lb cant seem to tell and I save a couple bucks...