The only way to be certain is to try it, but I am almost positive that your downpipe isn't the problem with your boost. It may have been weather related. Do you have a MBC or EBC? The heat wrap would only make a difference with how fast the air can move throught the downpipe, which may affect HP numbers but not the amount of boost you are able to hit. But, again trial and error is the only way to be ABSOLUTELY certain. If your anything like me, you are probably peeling off heat wrap ( an absolute bitch to do!) to try and gain back some boost. Boost is made before the turbo and at the turbo......so boost lost cannot be caused by parts after the turbo. Do you have a blow off valve?? with the change in back pressure a BOV could be bleeding off boost if not adjusted properly. Just throwing possibilities out there!