Read a report in BMW Car magazine about one fitted to E46 a while ago and it got huge thumbs up . This is a thread from the E90 forum ; ''First of all Thank you Birds! - Mr. Kevin Bird - great man! if you want to purchase your Quaife LSD, Birds is the place to get it from. They offer excellent support! That being said, i have finally installed the Quaife LSD on my 4 month old BMW. I did this operation at a small garage in Bucharest. They removed the entire exhaust then the main drive shaft and than the 2 rear ones. They then switched the differentials and mounted all those things back. It took them about 3 hours. After this I took the car for a drive but noticed a terrible sound coming from under the car. We concluded that the main drive shaft was rubbing on a exhaust shield and they reinstalled them again. After that, the operation was finalized and I was ready to test my new 335d In normal driving i didn't notice any difference (no strange sounds, no rattle or squeaking, nothing at all) compared to the OEM differential. I did all this on Friday and since that day it has been raining non-stop here. So, as Chris Harris, I couldn't have more perfect weather condition to try out this new differential From a standing start what you can notice is that you can get much more traction and you actually transfer a larger percentage of the power to the tarmac than before. You can barely see the the DSC light which eventually starts blinking around the end of the rev range (you all can agree with me that with stock differentials the DSC interferes very early and cuts your engine power very abruptly, this will not easily happen with Quaife LSD). When negotiating hard turns the grip level has been seriously improved and when you exist a corner it’s like you have been launched on a missile. That is the most important thing I have noticed after installing this LSD. What normally happens when you accelerate out of a turn is that you rear starts swinging and the DSC interferes abruptly and fixes your trajectory, which is good, but it also cuts your power and you can’t go forward as a 286hp car is supposed to. With the Quaife LSD you can feel that the rear is slipping a little bit but you can also gain speed like never before and even if the rear is slipping the DSC doesn’t interfere until very late. I haven’t had the chance yet to see how the car drifts but I’m sure you can get a much nicer sensation. What I have also noticed (it think that someone else mentioned this in a review) is that you clearly have more traction with an LSD but when you do loose it (!) things are much more serious than with an open differential, if you know that I mean….. I must be honest to end and admit the following think: my car is absolutely fabulous but there is one think I really don’t like about – you can’t use it’s power because of the power traction! Well….an LSD partially solves that problem! Don’t expect to get a AWD car after installing it, just and improved version of RWD car that still has to obey the laws of physics.'' and this from the Alpina forum ; ''Last week the Quaife LSD was fitted to my B10 3.3 by Birds Auto near Uxbridge, London The new diff fits inside the standard housing so measuring up and getting the correct sized Quaife unit was the cause of delay and the fitting took over-night; the final bill including new oil was £1,392.64 including VAT, the actual unit cost is £853.32 + VAT. Now I'm no hooligan and clutches are far too expensive so I've not been driving hard in the dry weather and to be honest there is no appreciable difference in the feel of the car on dry roads. I was expecting a bit more understeer but none has materialised and in fact the cars balance appears just as excellent as before. Additionally, no NVH has appeared since the mod. In the wet though it is a different matter, it's quite possible to give the engine it's head in 1st and 2nd gear out of corners without the ASC light flashing away and when you pull out of wet junctions the power just goes down without fuss or drama while the ASC light flashes just momentarily (I expect this is just the new diff transferring the power away from the spinning wheel to the non-spinning wheel) BUT you get no bog, bog, crawl, panic, fast - which used to be the series of events prior to the LSD fitment. It's still early days and I'm sure there's still lots to learn but it's taken a bit of patience and some cash to achieve but I am very pleased with the results.'' Hope this helps a bit