DDMworks Rotrex Supercharger Review

  • I’m done with the install of the DDM Rotrex supercharger kit and I now have 200+ miles on it so I feel like I can write up a review.


    I ordered this kit during the Black Friday deal last fall, took about 5 weeks to receive it which I thought was good given holidays. Then it sat in my basement to wait out the long cold MN winter. Occasionally (really multiple times per day, my wife will attest to that) I would go down there and check on it, go through parts again, make sure it’s all still there, just waiting for warmer weather.

    I gave in the first week of Feb and bought a garage heater....yay!!! Time for the install!


    the install took me several weeks of a couple hours here and there...doing a step or two each time I had a chance to work on it. I have twin toddlers and my wife is a tax accountant so I was working, being full time dad and trying to squeeze this in at the same time. The girls did help with tie wrapping some of the wires :). If I worked on it solid, I’d imagine a day and a half would be very doable for me. Only help I had was to remove the hood.


    The instructions were really clear, I did contact Dave@DDMWorks a few times via text and once over the phone to clarify a few things, every time getting a quick response that answered all my questions. The kit is really well made, designed and the fitment of all parts was great. I am probably average mechanical skills, maybe below average, and I was able to do it pretty easily. Just took my time. I did have to buy a few tools like a larger socket for the crank bolt, some shears to cut away the rear radiator shroud, grabbed tool and endoscope to retrieve a lost bolt in the bell housing (stupid mistake!) and modified an Allen key to get one of the bolts in that attaches the supercharger support to the front of the engine. I did not remove the radiator, would have been easier if I did that.


    Finally got it all together, worked up the courage to fire it up and took it for a first drive...it ran flawlessly!! It was really hard to keep the RPMs down for the first 65 miles of break in, which I finished the break in the next day. Once broke in I could let it rip...and this thing is wicked fast! Massive improvement over stock. I have had one quick car in my life (1995 Eclipse GS-T) but nothing like this, this is really my first true performance vehicle and it is so damn fun! I loved my slingshot since I test drove it back in fall 2016 and I love it even more now. The power is so smooth and pulls like a freight train. The blow off valve is addicting. I have the welter 2.5in exhaust as well and it sounds awesome across the entire RPM range. I smile and giggle like a kid every time I press the red button....heck I do it when I see it in the garage every morning!


    For anyone else thinking about adding a supercharger, you should do it! If you do, go with DDM, they make great products and stand behind them. I also have the DDM surge tank, fuel rail, sway bar, mounts and end links...maybe more I’m not remembering, they are all great products.


    Here are a few photos. I’m done with all the mods I want too do now...said no slingshot owner ever...time for wheel and tire upgrades!!

  • Install looks great, thanks for the review!

  • Looks really good, nice review.


    I know you said you were stopped, but when are you going to do the cams and smaller pulley? :)

    I’m sure that will happen at some point, as long it’s still reliable with a stock motor. Another 100 miles today and I’m starting to get used to the new power....so I guess it’s time for more

  • I have one also, albeit that I bought it from someone else. I bought my first SS in late May of 2016. I sold it after buying this one (thank you again bjk81 ) and haven't looked back! I kept some of the nice parts from my other one, bought new (other) parts to update this one, and in the end I have a nicer, tighter, better driving SS with the Big Kahuna package! Did I mention mine had just under 50K on it, and this one had just under 11K on it?


    The power is addictive! The mileage didn't drop that much, maybe 5 MPG from what I was getting before with the way I drive it. I have some highway, some in town, and then there's the PLAYING, which is addictive! With a sticky tire, it will really pull in 2nd (until it doesn't, about 5k plus) and 3rd!

    Happy you are enjoying yours, I know we are ours!!

  • Goats_Hogs i’ve noticed a mileage drop that’s for sure but I haven’t kept track. I find that I end up PLAYING more often than not!


    I’m starting to find the sweet spots in 2nd and 3rd where I can get it hook up pretty well and I just pulls. I’m running a nitto 555 right now, thinking I will get a different tire later this summer. I’m looking at wheels too, maybe a 305 or 315 will get more traction but so far I’m happy with it.

  • wickedwebby believe me, I’ve thought about the 4th wheel. It’s not out of the question but probably not in the near future. One kind of lame reason is I really like the size and shape of the SS for storing in my small 3rd garage stall. The single rear wheel allows for more toddler toy storage...but that need won’t be around forever.

  • Goats_Hogs i’ve noticed a mileage drop that’s for sure but I haven’t kept track. I find that I end up PLAYING more often than not!


    I’m starting to find the sweet spots in 2nd and 3rd where I can get it hook up pretty well and I just pulls. I’m running a nitto 555 right now, thinking I will get a different tire later this summer. I’m looking at wheels too, maybe a 305 or 315 will get more traction but so far I’m happy with it.

    On my prior SS, I had a General GMax RS, 275/35-20. On this SS, it came with a Nitto 555 315 (on SLR rim). That Nitto was worn about the same as the General. The Nitto (30% tread, then less) didn't stick well in corners, and 2nd was not usable much after 3k RPM unless I feathered the throttle. I finally switched to the General (less than 30%, only about 1/16" to the first tread wear bar) and was so much better! It will stick until at least 5k in 2nd, and I've not had it break loose under hard acceleration in 3rd. I will never have another Nitto 555 on my SS. I've been very please with the General GMax RS, and will be getting another on this rim soon. I already have one on a different rim that's not been on the road yet. I'm just not sure I'll get 10K miles on it with the supercharger, and I drive it about 12k a season.

    Good luck with whatever you go with. :)

  • Goats_Hogs i’ve noticed a mileage drop that’s for sure but I haven’t kept track. I find that I end up PLAYING more often than not!


    I’m starting to find the sweet spots in 2nd and 3rd where I can get it hook up pretty well and I just pulls. I’m running a nitto 555 right now, thinking I will get a different tire later this summer. I’m looking at wheels too, maybe a 305 or 315 will get more traction but so far I’m happy with it.

    I have been very dissatisfied with the nitto 555. I will definitely be going back to the T1R!


    Tim "Ghost" Ganey
    Winfield, Alabama
    205spam412spam2868

  • I have been very dissatisfied with the nitto 555. I will definitely be going back to the T1R!

    Yeah Ghost me too. I had put one on the back and when it was fairly new it got pretty good grip. Then all of a sudden it wouldn't get hardly any traction. I thought maybe the tire just went through too many heat cycles and got hard. Well I didn't learn and put a complete set on the Sling last year right before Maggie Valleyand they felt pretty good. Then I was too sick to ride in the summer heat so they just set there doing nothing until this spring. ............... no traction but they will let the supercharger work good.:00008862::00008862::thumbdown:

    ps They work pretty good on wet roads.

    :BLUESS:
    Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did do.
    ~Mark Twain~

  • Yeah Ghost me too. I had put one on the back and when it was fairly new it got pretty good grip. Then all of a sudden it wouldn't get hardly any traction. I thought maybe the tire just went through too many heat cycles and got hard. Well I didn't learn and put a complete set on the Sling last year right before Maggie Valleyand they felt pretty good. Then I was too sick to ride in the summer heat so they just set there doing nothing until this spring. ............... no traction but they will let the supercharger work good.:00008862::00008862::thumbdown:

    ps They work pretty good on wet roads.

    Even brand new the Nitto 555 G2 ain't worth a damn it is spin on demand any time you want it and sometimes when you don't. The worst tire of all that I have ran.

  • On my prior SS, I had a General GMax RS, 275/35-20. On this SS, it came with a Nitto 555 315 (on SLR rim). That Nitto was worn about the same as the General. The Nitto (30% tread, then less) didn't stick well in corners, and 2nd was not usable much after 3k RPM unless I feathered the throttle. I finally switched to the General (less than 30%, only about 1/16" to the first tread wear bar) and was so much better! It will stick until at least 5k in 2nd, and I've not had it break loose under hard acceleration in 3rd. I will never have another Nitto 555 on my SS. I've been very please with the General GMax RS, and will be getting another on this rim soon. I already have one on a different rim that's not been on the road yet. I'm just not sure I'll get 10K miles on it with the supercharger, and I drive it about 12k a season.

    Good luck with whatever you go with. :)

    I ran both of these posts through "Google Translator" and it was like, WTF language are they speaking? ...lol

    The world would be a different place if everyone listened to country music...

  • I am getting ready to replace my rear tire pretty soon and would love to try a Gmax rs - unfortunately it does not seem to be available in the stock 255/35-20 that I have been running - - thought about bumping the size up so long as it would fit the stock rim, but larger sizes seem to be disproportionately higher priced - on discount tires a 255/35-20 G555 is $144 - - even the small jump to a 265/35-20 and the price jumps to $211


    Are there some sizes that are just more popular and there fore less $$ - and if so is there another size that would fit well on my stock 20 inch wheel that might make other tire options available at reasonable prices?

    Cage Free - 2016 Pearl Red SL

    DDM Short Shifter, Sway Bar Mounts & Master Cylinder Brace

    Twist Dynamics Sway Bar, JRI GT Coilovers, Assault Hood Vent

    OEM Double Bubble windshields & various other goodies