Customer Testimonials

Customer Testimonials

What Our Customers Say

"I went with a 3.64 3 Clutch setup with 45/45 ramps for my E46 ZHP. It completely changed the driving dynamics of my car. Throttle steering is now predictable, corner exit speeds have increased, snow traction is incredible, and the fun factor is priceless. The best part = it feels like a OEM BMW differential. All of my future BMW differentials will come from diffsonline."

Wyatt A. Gilbert
Motion Control Suspension

"Couldn't have asked for better customer service. The car feels like a brand new car. The craftsmanship that goes into their work is top notch. I will definitely be spreading the word to anyone in the market."

Rick Vazquez

"Outstanding Craftsmanship, Perfect Customer Service, Timely Scheduling, Eagle Eye For Detail. I definitely recommend this company to anyone looking for Quality, Precision and Professionalism."

Dave Gallagher

"Dan, The diff we had in the Bullet E90 328i for the 25 Hours of Thunderhill was awesome. Thanks for your support!!! We basically kicked ass!!!!!! Cheers!! Car: 2008, BMW 328i, 6-Speed"

Ralph Warren
Team Sparta Evolution and Bullet Performance

"Exceptional personal service and a vast knowledge of what we needed for our "One Lap of America" BMW M3 car!!"

Mark Hampton

"Lifetime customer here! I had two units from Diffsonline on my first E36 M3 (street car turned race car), another on my next dual-duty E36 M3, another on my supercharged E46 325iT über wagon project car, and now setting up for yet another on my current Project E36 M3. Safe to say I've been very happy with the diffs, and the quality and longevity have been much better than those I've witnessed from other companies. Plus, Dan has been great and patient with helping to pick the right spec choices for each application. My early cars were great on the street and track, but now I get to really enjoy the Diffsonline LSDs for triple duty: Street, track and real weather I didn't get before moving out of SoCal (snow is a whole new world of fun)."

Jonathan L.

"Picked up a transmission at Diffsonline today. That business never fails to amaze me! It shows what can be done when one approaches building a business with intelligence, diligence, and creativity. The American Dream is alive and well in Wilmington, MA. Always so fun. If Dan Fitzgerald wasn't so damned busy working I'd spend a lot more time there learning and BS'ing about race cars."

Thomas Rossi

"I guess we will have to say that the 4.27 gears work well, at the very least, won't we? I knew on Monday that the car would do better than my 1:03, but I never in my wildest dreams thought about a minute flat! Let alone a new track record!!!! But then, I was on the hillside watching--Andrew didn't do too bad in his 3rd club race, and first day in my car--maybe I should invite him back! Thanks for your part in getting me the set up that allowed the record to fall to Andrew."

Whitman Ball

"Having been away from home racing for 3 weeks now, there is plenty of work to be done to get the #03 DM car ready for the next race. ... Dan at Diffsonline has jumped through some serious hoops to provide a superb drivetrain. The race diff and new tranny I got from Diffsonline are awesome!"

Mike Akard

"First off, I love my new LSD. Thanks to Dan from for the great build. As for driving, the newfound acceleration on my 328is is great. No more low-torque lag around 2000rpm, now it has a much fuller powerband and is noticeably more ballsy. This is definitely the best mod I've done so far, as it has allowed me to actually use the horsepower my car has much more effectively. As for the limited slip part, I love it. I have always knew I was missing out by having an open diff. From driving other cars, I have always been a fan of the limited slip and I feel that it is the true way to appreciate a rear-wheel drive car. I'm amped on the fact that I have an LSD now. Can't wait to do some donuts! Anyone else running a 3.46 from diffsonline?"

"I wasn't originally going to do a new differential in my car just yet, but I'm really glad I did! A sneak peak into my diff before it was built, and the internals were beautifully polished. Comparing a stock, unpolished diff to a DiffsOnline polished diff, the difference in effort required to spin the input flange was incredible. The polished internals made everything so much smoother and easier to move. And after it was installed...the only word to describe it is "wow." The 3.46 ratio is a wonderful complement to my cammed M3, and seems to be the perfect ratio for this application. I'm still on snow tires, so it's hard to judge the increased traction of the 40% lockup, but it seems to be greatly improved and more predictable than stock. I pulled the ASC out long ago, but it seems even easier to drive in slick conditions now."

Corwyn M.

"Hey Dan, Just installed the 3.46 Yesterday and I gotta say, I LOVE IT! It feels great to use the horsepower my car has much more effectively! I love having the limited-slip too, it's awesome. This mod totally changes the whole attitude of the car...much more aggressive now! Thanks again for the great build Dan, I'm enjoying every minute!"


"I recently decided to upgrade my 1990 e30 325i with a Diffsonline 4.10 lsd. I went with a 50% 3 plate clutch set up, because it was a great compromise between street and track for my needs. All I can say is wow! The bottom end is amazing, it feels like no matter where I am on the tach, I have acceleration. While I lose a little top end, I find it's worth it for the amount of low end power. The car feels better than ever and I couldn't be happier!"


"I got a 3.38 dropped in about a month ago and it didn't do as much as I hoped for. I can tell the revs are up but only by a little bit. I feel the LSD way more than the gears. I was quite surprised how much a lsd could do to the way a car behaves. In the future I'd go for a 3.46"


"I'm loving that 3.23 lsd you put in my car yesterday. The acceleration improvement is mild but definitely noticeable, about what I expected, but I'm amazed at how much I can feel the better traction, even just on the street at about 2/3rds the Limit. Of course it snowed a little this morning, so I got to fool a bit with that too."


"Chris from Melbourne Australia here. I installed the Differential that I purchased from you today, and I must say that I am extremely happy with your service, professionalism and quality product that you offered at a very affordable price (i might add). Delivery was incredibly easy, even more easier than purchasing a product from Ebay. I have spoken many good things to many people about your excellent service, and have recommended you to many friends, colleagues, and even businesses about your service. Hope all goes well for the future. =) Many Thanks."

DTM Power