First things first. If you are going to remap your Boxer Diesel, you will NEED to get a better clutch. Unfortunately that is easier said than done, as nowhere really sells an off-the-shelf uprated clutch.The stock clutch (which is a Sachs piece) is terrible and will almost certainly start slipping even on a non-remapped Boxer Diesel. On a remapped diesel, it will slip immediately.Due to the lack of choices, I went with a modified Sachs OEM clutch from ZF Sachs in Germany.Link: http://www.sachsperformance.com/product_info.php?language=en&products_id=313If you are going to get this clutch, it doesn't come with a release bearing, so you'll need to get that from Subaru Genuine Parts.I have been using the ZF Sachs Clutch Kit now for over 1 year remapped, and there is not a hint of clutch slip, so I can only recommend it.The other problem related to the clutch is the Dual Mass Flywheel. This is a device intended to prevent diesel torque damage to the gearbox, along with reducing diesel chatter and reducing vibrations.The Dual Mass Flywheel has two parts, with springs that soften the initial torque load on the clutch and transmission and eliminate any unwanted chatter.Dual Mass Flywheels are good in that they mean damage occurs to a a fairly expensive flywheel as opposed to a hugely expensive transmission, but they are not good for performance diesels, adding to sluggish response and prone to failure.Dual Mass Flywheels however are fairly delicate, however I have found that the Subaru version, manufactured by Sachs, is actually quite hardy and has survived one year at 200bhp with no issues. I did however replace my DMF one year ago as a precaution, as we were replacing the clutch with the ZF Sachs kit. It was very expensive. A brand new Subaru OEM Dual Mass Flywheel is about 970 UK pounds. Thats around 1600 US dollars!Now, Manfred Stohl, who uses an Impreza Diesel as a rally car, which often wins its class, has developed a solid flywheel. This I hope to use when the Dual Mass Flywheel gives up. He also uses a sintered metal clutch, but thats a bit overkill for a daily driver!UpdateI have been told today that Exedy now offer replacement clutches for the Boxer Diesel, listed under Forester section. They even offer a Single Mass Flywheel! They don't appear to offer an uprated clutch though, which is a shame.I would like to see more information about their SMF, as If I'm going to the hassle of changing the DMF to SMF, then I'd rather go for a lightweight single mass flywheel.