I'm looking at both options and need some users advice. First of all the price difference, Needswing dual CAI sells for $800.00 whereas the TVT's SL55 installation is $700.00. Needswings claims an increase of up to 35 RWHP, TVT states 26 RWHP. Have any of you tried both and was there a noticeable difference. Are the RWHP claims correct?? I do like the original look of TVTs but I'm curious to know whether the top cover still fits on? I think I saw somewhere on this forum recently that someone made a modification to the brackets for the cover to fit. Anyhow, I'm sure I'll receive various opinions but at the end of the day which of these provides the best results. I look forward to your replys.