They are not perfect on stall speed but honestly once you get it you wont check it anyway. Its that much of a difference having a real converter over a D5. As for the single vs 5 disc its up to you. I personally would not want to risk a single disc locking up at WOT but as BOOST231 says it can be done. Street car=single disc Race car=5 disc and leaves nothing on the table to wish for. There are lots of opinions on this so dont take our word for it. Personal preference for the most part. HTH