Never had a problem with my 998GT-R, started 1st go upon installation, gave it a run in tune, I ran it in within a week... Other than it seeming to run a little hotter than normal for awhile until the k's started getting up there it was mint, but now it's all back to normal temp's, it start's first go everytime and feel's and sound's tuff as nail's, cant wait to really start throwing power into it...