EFI on any engine is kinda neat, but since nobody had the right reply, I will fill you in. You can have it idle as aggressive as you want or as mild or milder than your set-up now.
Generally, most tuners will get you the strongest idle possible. This generally translates into smothest and it will definitly be smoother than your carb. Now once you have the best idle you can get, and you want that muscle car lope back to it, a little change in the fuel table and timing table and its back to its usual sound.
Basically, you have to create a bigger difference from point to point on the fuel table in the idle position, and put in a little more timing in at idle. Also, there is a timing trim table that helps to stabilize the idle, and you can reduce that a little which will allow the engine to climb a little before bring it back. Generally, its easiest by bring up the initial timming and setting bigger differences in the VE points closest to where it idles in the fuel map. Also, you can cut the gain down on the IAC.
I run a street program and a race program in my hemi because of the bug catcher it only rotates about 87* to WOT, and having all that timing and fuel come in as quick as the engine will take it can make for some scary driving. In full race mode, it sounds like a pro-stock car, and in street mode it sounds like a mild mannered big block until you step on it. I also change the exhaust over to a 3" set of flow masters for the street as well. The 3.5" bullets with turn downs on them are really only race legal and really loud.
