I’ve read some very negative things about Hennessey and the way they do business. I wouldn’t give money to a tuner anyway - any mods I’ve ever done to my cars have been minor things I could do myself - but anyone planning to hand over a big check to any tuner should definitely do their homework first about the company’s track record of business practices.
Ex-Employees Say Hennessey Is A Bigger Mess Than You Ever Imagined