Well i've been ironing out the kinks in this car with the EU, i changed the V2pulley to a 3.125, made a CAI for it etc. The car has venom injectors(370cc)in it and i have a feeling they are not flowing the same(one bank runs richer than the other according to the fuel trims) so i'm installing a set of deatschwerks 450cc. While i'm there i'm also removing the lower to replace the knock sensor. I am wondering if there is anything to gain by changing the lower intake manifold since this is a 99 cali car and it has the swirl valve. I have 3 regular lowers laying around. Thanks

 

The swirl valves do look somewhat restrictive. I would remove them or swap an older 4th gen manifold