currently have a 2013 XKR and I was considering an APR upgrade wit ECU, Pulley and exhaust. Has anyone had issues with the computer after an upgrade? my local dealer said he had to replace the whole computer when the engine light came on

 

With a pulley upgrade and a remap I don't think you'll be seeing much more than a 15% increase in either BHP or torque, probably more like 10.

But with 500BHP to start with that may be enough for you. Can I ask when you believe you'll be able to put down all of that power?

With a 13 you'll have dynamic driving mode, which I'll assume you drive in permanently & this isn't enough and you need more.

Have only remapped diesels, in my A6 it was predominantly for economy but on dyno it still gave me a an extra 20bhp over the the stock 233

Would recommend the best tyres you can afford Michy PS4's spring to mind, as putting down any more power may be interesting, esp with the colder/wetter weather upon us