Start with stock and follow one of the guides. I started with a non-stock/canned tune and regretted it. I struggled to get my maf tune right because the injector flow rate had been messed with and I fought KR for a long time due to a bad timing table. Scotty was actually the one to figure it out. The problem with a canned tune is you don't really know everything that's in it. If anything, start with stock and copy over just the pieces you want to try first.