I have put roughly 25K on the modded manifold before it started to fail (leaking vacuum at idle mainly) The interesting thing to me now is that I am having far more trouble getting the damn thing back together and functioning properly. Interesting in that when I half assed it and glued it together before, it worked almost immediately. I had some minor teething issues with porpoising but that was quickly fixed with more glue LOL Now that I am doing it the RIGHT way (plastic welding) its been a bitch kitty getting the blasted TB neck to seal properly. Had her on and off the car five times this weekend without success. Its got a massive air leak right at the TB around the top side that is VERY difficult to get at with the welder. I shall perservere though, I got it working once, I can damn sure do it again.