I have just put my bmc cda on the car and its made no difference in terms of power loss/gain, throttle responce or noise etc.
Some thought it might be to constrictive as its enclosed.
Obviously without having it rr'd or having a afr gauge i cant tell if its made any difference to the way the car behaves.
I am assuming it would help with heat soak being enclosed but my car has never seen a track car park let alone the track so i have no real way of testing it.
Looks cool though
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***Breaking*** Ph3 Silver GTI 6 High Boost