Can any 1 help any advise would be greatfull here`s my problem my car useuly boosts at 1.8 but now it only boost at 1.0 and it also makes a rattling noise wen you hold it at 3k sounds like it coming from the front right corner the only thing that i have done is change the coil to a group A but that wouldn`t effect owt would it or would it many thanks .