I think you are missing the point...... the yoyo affect is nothing to do with the GTT conversion..... it does not cause it.
GTT’s reputation should give you all the reassurance you need...... however if you are a worrier by nature then best stick with a non modified car….. any modification requires you to trust your tuning company / mechanic.
I personally would not hesitate to get a conversion done by GTT.
Cheers
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