[Balr14]

There is a staggering number of upgrades options available for the N54. So, I need some help. I have a 2009 335i xdrive sedan with 6 speed manual. I would like more power, at least as much as my 2018 Mustang 5.0. I also notice it really drops off between shifts, way more than other turbo cars I have owned before. I am open to most suggestions, but I don't really want to change the exhaust. I'm happy with the general lack of noise.

The car has 65k miles and has been well maintained.

[nic_hender]

Power Mods without changing exhaust
Intercooler
DCI
MHD Stage 1+ e30 tune
If you want more power you either need to go catless downpipes and stage 2 + or upgrade your fuel pump to run higher ethanol blends.

Safety Mods:
Chargepipe

Go with VRSF or any brand you like, I would stay away from ebay stuff but you do you.

[mike@x-ph.com]

Tune + Downpipe + intercooler + Charge Pipe + intake

[Balr14]

Is there something wrong with my current intercooler?

I don't think we have E30 around here. I can get E85.

What kind of tune? I see there are several types.

[Emilime75]

Too small and inefficient, barely passes for stock power and even then sometimes not sufficient. If you're doing any power upgrades, include an upgraded FMIC as a necessity.

Most will suggest MHD for the tune. JB4 is another good option. Some like both, you get safety features with the JB4 while the MHD is a better all around tune.

You can do E85, but will need additional mods beyond the "FBO" stuff to support it.

[bimmerguy1210]

Before you tune, change your spark plugs/coils and walnut blast your valves if it hasn't been done yet.

You can mix e85 with 91 or 93, whichever you have access to, to achieve an e30 blend. It will tax both your stock fuel pumps however.

[tisdrew]

MHD has a 'shift bog fix' option to eliminate the boost drop you mentioned. If you get a custom tune from motiv, I believe they could set you up with flex fuel, NLS, and other niceties all through the MHD flash-only map.

[N54_ABQ]

Definitely take care of any maintenance before upgrading anything. As bimmerguy1210 mentioned, spark plugs and coils are a good thing to replace up front. That will help you avoid misfire issues when you do start turning up the boost. OE plugs work well up to 350-400HP. Colder NGKs are best for anything above that.
Any other issues like leaky gaskets/seals and sensors that throw SES lights will only get worse once more power is being made.

As already mentioned, intercooler and downpipes are about the first parts that will get you the most increase up front when paired with a tune. The next things will be inlets/DCI and chargepipe/BOV. VRSF has some good options here. Cheap stuff is not worth it. A few extra bucks goes a long way to avoid fitment issues.

For fuel, the stock system handles increases pretty well given the pumps and injectors are healthy. When running ethanol blends it is a good idea to upgrade the low pressure pump to at least a stage2.

For tunes, MHD is a good place to start. Its fairly inexpensive and there are many maps depending on the setup you have. From there the JB4 is a good option for user tunability and safety features. JB4 can be used in addition to a flash tune or "backend" flash as its commonly known. This especially helps when running ethanol blends and upgraded turbos.

From there its all about how much money you want to spend. The sky's the limit.

[Jeff@TopGearSolutions]

Lots of good info here. If you need any further help let me know.

[Balr14]

Thanks. Lots of excellent info.

Will the AWD handle power upgrades?

[bimmerzeit]

Good advice here. I am removing the split second turbo tuner the previous owner installed and going with MHD. Just did one-step colder plugs and new Bosch coil packs to prepare. Might smoke test to find a pesky 30FF code and/or replace the stock plastic charge pipe.

[Jeff@TopGearSolutions]

Originally Posted by Balr14

Thanks. Lots of excellent info.

Will the AWD handle power upgrades?

Good for about 500HP. After that, it depends on abuse.

Originally Posted by bimmerzeit

Good advice here. I am removing the split second turbo tuner the previous owner installed and going with MHD. Just did one-step colder plugs and new Bosch coil packs to prepare. Might smoke test to find a pesky 30FF code and/or replace the stock plastic charge pipe.

Replace all the vacuum lines too.

[turbohugh]

Originally Posted by Jeff@TopGearSolutions

Good for about 500HP. After that, it depends on abuse.

Replace all the vacuum lines too.

If you haven't done it a walnut blast will wake up the car. It's recommended every 50~75k I'd do it earlier and get a good PCV system on the low side

[Balr14]

Do dealers do the walnut blast and what's the cost estimate?

I think I like the CSF intercooler. Good choice?

Also, I would not go catless. So any upgrades would have to work with cats.