Hi Chris, good to see you back on here mate

I know Scotts working out of bently now so he would be the best person to ask about the stock exhaust modifications.

The varex are amazing. I had one on my 04 STI the best idea ever with single system. Stealth mode just flick the switch. I had a Buttler system but this was just to loud for my requirements.

Yes you will need a tune with the exhaust, but you can get a Cob access port for this model now. Don't get locked into a tuning format, ie Ecutec

I have a 15/16 with the invidia system if you want to go for a spin to see what it sounds like. The quality is faultless

You can also get a copy system at Vison R, looking at this system it's amazing quality.