UPDATED RECOMMENDATION (May 22)
Until now, we discussed that the Kia Stinger stock spark plugs can have issues in combination with bad fuel quality. Now we have seen an issue with stock spark plugs in combination with 94 octane (see posts above). For this reason we adapt our recommendation.
We do not want our customers to have any hassle. We are aiming for a 0% issue rate and 100% customer satisfaction (I know we have some more way to go when we are talking about the Kia Stinger). Accordingly, we now start highly recommending using performance aftermarket spark plugs instead of the Kia Stinger stock spark plugs.
Quite a few RaceChip customers re-gapped their stock spark plugs to 0.024-0.028 (from stock 0.034-0.036) and report good performance. None of them had any issues so far. So, re-gapping the stock spark plugs might be a good alternative to replacing them. However, we did not extensively test the re-gapped spark plugs in the US, so our official recommendation will be replacing the spark plugs.
Notice: This recommendation affects only RaceChip performance upgrades and not our throttle tuning XLR. RaceChip XLR does NOT require replacing or re-gapping the spark plugs.
We apologize for this inconvenience and we are sorry for the fact that we changed our recommendation 180 degree compared to the beginning. Some of you will be disappointed now. We'll do our best to win your trust back. The issues reflect only a small single-digit percentage area of all Kia Stinger owners with a RaceChip. Though, we take it very serious. RaceChip is offering products for 4,000 car models and this is the first time that users are dealing with poor spark plug quality.