Try it out with the check valves and see if you like it. I ran TTC when I had my stock DP for awile it it wasn't too laggy for me, but somepeople with a DP think it's too laggy even with a DP, so try it for yourself.
Lag is way too subjective... a guy a few days ago said he did TTC on his auto with the stock stall converter and said there wasn't any lag at all... only to have someone reply and say that they could NOT STAND for the LIFE of them TTC on an auto with the stock stall... if you have a 6-speed I don't think the difference between no cats and highflow cats will matter that much. Why are you going to go from no cats to a highflow? Emissions I assume?
Yep! I put the high flow on recently when i noticed lots of smog check stations poppin up in my neigborhood...i want to do TTC but was not sure if the high flow cat was going to make it too laggy... i still have my stillen dp, and was thinkin if it is too much lag, I might just put that baby back on! Thanks guys!