I have the takeda CAI. The restriction from the bending you have to do to the silicon connectors to fit them through is pretty huge and due to that, the bottleneck seems greater than stock, although they are probably less restrictive everywhere else.
Because of this, I cut out space for them last year so they could be round. Just for peace of mind.
I then got the car tuned and made good power but power dipped a bit at the top couple hundred rpm. I didn't care too much since the rest of the curve was good and full, but if you really care about peak numbers, it's something to keep in mind. I also had other mods though, like a single HFC at my XYZ pipe, which may have also been the cause.
Definitely enjoy mine though, and I got it for $200 cheaper than the Gen 3 from Stillen.
But if you want the best, I think Stillen's is still the most recommended.
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