I went with the Thrasher on my '99GTP. I had a turbo set up at the end and pulled low 12's all day long on low boost. I was very happy with the thrasher as it was more 'user tuneable'. I had a zzp pcm with increased line pressure and and cooler... never gave me a problem. Heard bad things with the zzp kits and that was direct from zzp themselves when they first marketed the product. I don't think they revised as it worked 'well enough'... go Thrasher and you'll be happy from mild to wild.