Piggytune rated 370 HP, 340 foot pounds. I assume that is at the crank?
And does it plug into the rear of the ECU?
You are correct, that is crank hp. The piggyback tune does connect directly to the ECU using all OEM quality harnesses and connectors.
The Dinan of VW? Dinan have their own driveline warranty for BMW's, since BMW won't cover tuned cars. Does ABT have their own driveline warranty for VW's?
In Europe, ABT is actually more like Alpina to BMW than Dinan as there are full ABT equipped and limited edition VW vehicles that roll off the showroom floor. ABT does have their own drive train warranty... Per ABT Germany:
ABT Sportsline offers the best warranty solution on the market with 2 years warranty up to 100.000 km from the date of the first registration. The warranty is included and will be offered in following countries: Germany, Austria, Netherlands, Belgium, Luxembourg, Sweden, Norway, Denmark, Finland, Italy and Poland.
Together with their partners and distributors outside of Germany ABT Sportsline offers a broad range of warranty solutions. Due to country specific regulations differences may apply. For more information please do get in contact with the ABT partner in your country.