as a viper owner i am well aware of the stigma surrounding john and his shop. I tried to order parts from him before but didnt get any response so ordered elsewhere. As a result i cant really comment on his service or parts quality.
I do know however that the guys at underground racing were building the best TT setups on the Vipers when i was active on the forums in late 07. Garth (a UGR mech and driver ) ran a 7 second quarter pass in his street legal pumpgas GTS.
If anyone was looking to TT an SRT8 id recommend asking them about it. All the guys who went through them said they had great customer service