Flip4prez

Hello all,

Just bought a 2008 535xi 6mt e61 a few months ago, in monaco blue over beige. I love love love it a lot. HPFP, water pump, turbo wastegates already done before purchase.

I daily this about 28 miles each way on a highway in the high rockies of Colorado. I want to make a few modifications to it, and basically the only way I'll be able to justify modification costs to my wife is if they improve fuel economy. The mods pay for themselves is my angle.

I know that there are some N54 mods that improve fuel efficiency while also boosting power.

So here are my questions:

1. I want catless downpipes. Does this improve fuel efficiency? Is it legal to resell the car without those cats? I live in a rural area so we don't have to take emissions tests at all. I know the $850 ar downpipes are bolt on, and the VRSF ones involve some ghetto work to fit. Does anyone know if these ARM downpipes for the 335xi would fit the e61 535? https://www.armmotorsports.com/335xi...-p/335x-dp.htm ..... only $267! I know I would have to get the MHD app to keep the check engine light off.

2. Walnut blast diy? As easy as it seems? I already own an air compressor and shop vac.

3. Rims. It kinda seems like the offset is funky for the e61. I've got blizzaks on my stock 17s right now, and I threw out the ones that came with the car because they were worn. I figure I can buy new tires and rims and in spring and go to 18s without affecting fuel economy. Any best practices for e61 18" rims? offset?

4. In general, what's my play for improving power and also fuel efficiency?

5. M-Sport bumper from umnitza, prepainted looks like the way to go. Anyone have experience ordering that?

Thanks in advance to any and all.

MysticRob

1. I wouldn't bother with catless DPs, just go with an MHD Stage 1 tune and see how you like it. DPs on AWD cars can be a huge pain. Removing cats does nothing for fuel efficiency, just smells up the exhaust more and removes restriction, thus improving power from 20-35hp depending on whose dyno # claims you trust.
2. Ensure your compressor is up to the task and your blasting kit is good. Otherwise, pretty easy with the right tools to get the intake off.
3. I went with 3-Series wheels with a decreased 34 offset (from stock 43) to push the wheels out farther and make the wheel well gap less noticeable on my 17s. My own calcs told me offset down to high 20s would still fit and look good.
4. MHD engine tune, and xHP tranny tune. Best of both worlds for driveability. I love the xHP Stage 1 tranny tune, totally matches my relaxed driving style in town.
5. No idea on bumpers, but I'd be leery of having a painted bumper shipped, as I'd rather prep and paint it after shipping to avoid any damage.

Flip4prez

Thanks for the replies. My e61 is a manual, does a tranny tune work on a manual?

MysticRob

No, I'm just high from spray painting things at work and missed that part.

Sixracer

Admittedly I am no expert (yet) having owned my own 2008 535Xi 6-sp for only about 6 months. I took care of most of the big maintenance jobs but still fiddling with smaller stuff (thigh support, tailgate wiring, etc). I am assuming you are not a first time BMW owner so I will spare you the "save for maintainence/repairs first" lecture. I assume you did spark plugs, coils, driveline fluids, brakes, cooling system components, and anything else you don't know the history of. How is your suspension? I am sure your car could use some attention there.

A stage 1 MHD tune is a must right off the bat. I picked up a nice Bimmergeeks cable and a dirt cheap Amazon tablet to do it.
Pairing that with dual cone intakes is also easy. Probably cost me $500 with all the software, a tablet, the cable, intake, etc. (Note it wouldn't hurt to do coils and plugs before the tune) Going to aluminum charge pipes (instead of the stock plastic) is likely next for me to support the additional boost.

On my car that was good for 400 HP at the wheels and 0-60 in about 5 sec flat. Plenty for dropping the kids at school!

Roads in Boston are terrible so this isn't high priority for me, but perhaps would be good for you....filling the wheel well/lowering/wheels/tires. Can easily spend a lot there but ROI is high in my opinion. Sounds like you are on this. If I lived in a smoother part of the country i'd go for 19" wheels and increase OD to run a 40-profile tire to fill the wheel well. If you do plan to use in winter, drop might not be best move.

ucsbwsr

Before I focus on some of your more specific questions, the biggest advice I can give is to continue researching your questions on the internet. Most of the general questions posed have been discussed (over and over and over) and some of the other questions like "how hard is _____" we can't answer since we don't know how skilled/experienced/crafty you are; it's better for you to research the process until you understand what is involved and can assess how hard it would be for you to do. But if you have to ask "how hard..." then my response is "probably hard if you are asking." Don't mean to sound like a punk but I do think it's important to be blunt about this as it's best for everyone in the long term.

I would also reflect on what your goals are for the wagon, having that established will make it easier to decide what your priorities are and what mods should be done and which should be skipped.

Getting onto more specific questions. Anything related to freeing up airflow in and out of the engine + turbos will increase efficiency as well as power. The challenging part if driving in an efficient manner when you know you have some good power on tap. For the short period of time I was full bolt on and running pump gas, before ethanol and hybrid turbos, I was seeing around 30mpg on the highway so yes, the bolt on mods like DPs, inlets, outlets, cold air intake, intercooler, etc. will improve efficiency. Stay away from E85 is mpgs are important.

"Trans tunes" are for autos and not applicable to your MT

For wheel specs/offsets, it depends on what your goals are. Looks? Grip? Efficiency? Square, staggered. Again, Focusing on your goals will answer all these. Wheel specs can be overwhelming at first but I would recommend taking the time to learn what the terms mean once you know that it's pretty easy to figure out what will work and meet your goals. What I do if find setups I like make note of their specs and use a wheel calculator like www.willtheyfit.com and plug everything in. In addition to wheel specs tire size, brand, ride height, and intended use all play a part in if a wheel will rub etc. so don't expect people to offer a magical setup that will work for you unless they know all the details. Fitment is a personal thing and it's best to arrive at your own conclusion.

335xi DPs will not fit the 535xi. ARs are worth there money IMO since they are direct bolt on and they hold their resale value well since no other company has figured out how to built a bolt on DP. You can sell a car without cats.

I run a JB4 with an MHD back end flash. JB4 is powerful and includes features MHD doesn't have. MHD nickel and dimes you for various licenses to unlock all features. JB4 gets a bad wrap since people don't know how to set it up properly. I have been running it for the past 5 years with excellent results. Again, depends on your goals. Personally I like that JB4 has port injection integration and some more advanced features.

Based off your mention for efficiency and power, I would first go through some of the other E61 and N54 related issues and if nothing else mentally prepare that they might need attention (some definitely will) need attention down the road so that you don't start modding, get injector codes, and then get upset that a set of id12 injectors are $1,000. Engine, trans, TC, steering, brake, coolant flushes are always a good idea. New spark plugs should also be done since it's easy and will make diagnosing coils easier.

Also, invest in a K+DCAN cable of BT dongle and coding software or some sort of daignostic software where you can read module codes and ideally do coding, adaptation resetting, and basic functions. This is CRITICAL when tuning an N54 otherwise, you're going to have a bad time. At some point the wagon or engine will have issues and without this you won't know what's going on.

Assuming all maintenance is up to spec or at least you are mentally prepped for their failures then I would mod like this:
- High and low load OCCs
- DPs
- Turbo Inlets/Outlets
- Intercooler
- Charge pipe
- jb4 or MHD

This would be a nice free flowing setup for pump gas.

Evan

Flip4prez

Thanks Rob, Sixracer, and Evan. Really kind of you to take the time to respond. My HPFP, turbo wastegates, and steering flush were done before purchase. I flushed the cooling system, and replaced a cracked coolant pipe over the radiator. I changed the transmission, TC, and diff fluids after purchase. Spark plugs, Coils, and Walnut Blast next week.

@ucsbwsr My goal is definitely to just have a smooth running, well maintained e61. Going to go for 17's with big sidewall, for a smooth ride. Keeping my blizzaks on the oem wheels. The only reason for the MHD is that I feel like the 8 psi max stock is lame considering how much higher is possible. No need to push the horsepower as high as possible, but I at least want to be able to run a reasonable psi. I found it really interesting that you think the OCC is the FIRST thing you would recommend. Why is that? Do you have a specific one you recommend? I found a couple with a cursory search.

ucsbwsr

N54s can handle nice power easily if setup and tuned properly, an extremely reliable 500-600whp is possible but beyond what you are after ATM. A full bolt on setup should put you in the 400+awhp range which is a lot of fun and the N54 can take in stride.

The mods I listed are in no particular order in terms of importance. OCCs are great as they help limit carbon build up and makes your life easier in the long run. Personally I run the RB low load OCC and the BMW high load OCC. Both serve a purpose but if you only get one the low load is the way to go as it catches much more oil during daily driving.

www.N54Tech.com and www.SpoolStreet.com are excellent resources for the N54 motor. If you get a JB4; BMS owns N54Tech and posts their firmware JB4 updates, menus, and guides on that forum. It's great stuff.

Stroker396

I have a great meme it says "CAR GUYS DON'T CHEAT IN RELATIONSHIPS, THEY JUST LIE ABOUT THE COST OF PARTS"

Sounds like your best bet is to shop smart and save where you can (without sacrificing the quality). Aliexpress (China) has khatress DPs that will fit the 535Xi. Good used JB4's can be found both on Forums, FB Marketplace or ebay.

I just got an E60 535i MT, did my research and now buying my parts. The JB4 lets you change maps on the fly so go from stock to higher boost at a stop light. Multiple maps and much more = Awesome (combine with backend flash options) Vs. 1 tune and being charged over and over for each new tune No Thanks!

DCI for 70 shipped google is your friend.

You will need the port adapter to do the walnut blast. I 3D Printed my own. You can check etsy or hit me up.