I do the same with Lucas. Obviously Chevron, Redline, etc do not recommend such high concentration because of possibly lawsuits, but if you're careful, the results can be pleasing.
Lucas says their 1 quart bottle will treat 100 gallon (or 3oz for ever 10 gallons). I dumped half the bottle (16oz?) in my tank and pumped 5 gallons only. After driving around for a while, my shaky idle was disappearing and pickup speed was better. There will be smoke on start up, and that can cause an attraction
Even if you maintain your car well, you eventually build up deposits. Some argue that it's not necessary because gasoline already have additive packages in them (chevron w/techron). You'd be a fool to believe they dump that much in to make a real difference on your car. If anything, it just helps maintain an already clean engine.