Depends on location & its winter now. The IS has additional water cooling radiator, faster pump & IIRC bigger fan etc, then the stock 335i so it would depend on the weather. Without an LSD you would will spend a lot of time recovering from wheel slip as on/off/on the power does not make this car a happy camper without a tune to control lag.
Don't know what you experience with the car is but if you are under 1200 miles the car will change a lot with the full boost is made available by the ECU.
2014 435M-Sport - 2013 135is Cab JB4/ISO 6MT - 2009 V-Star - 2009 Ford Expedition EL 4X4 - 2003 Xterra 4X4 - 1998 Ranger 4X4 - FFR Cobra MK-IV
work in progress