2004 325XI Build

Updated: 09 Dec 2024

Hello all, I’m currently working on a build of my 325XI and I am focusing on beefing up and reinforcing OEM components prior to adding power or doing any serious engine modifications and I was curious if there is anything I should at to my list of things to do. See list below.

Done

ECS Tuning Rear Shock Mount reinforcement plates
ECS Tuning Aluminum and Carbon Fiber Front Strut Bar

To Do

ECS Tuning Aluminum Pulleys and High Performance Belts
Stewart High Performance Water Pump
ECS Tuning Hydraulic Alternator Belt Tensioner Conversion Kit
Beisan Systems VANOS Seals Upgrade Kit
ECS Tuning RTAB Upgrade and Limiters
ECS Tuning Aluminum Oil Filter Cap

*Note: Please don’t tell me to get another car or that this car isn’t worth it because I want to build on this platform and have something incredibly unique. I am also working with multiple BMW Performance and Racing application Tuners to help source or otherwise have parts made that would be otherwise non existent or hard to find. I also chose this car because I wanted a newer E46 chassis (due to its amazing capabilities as a chassis) with AWD. Also note that this list is for parts that will help improve reliability and will be able to handle more power when power is added (NOT parts that will increase power).

Comments

Some components I’d particularily like to upgrade or reinforce are the axels (front and/or rear) and other drive/suspension components (I’ve already gotten and installed Koni Yellow shocks and eibach springs).

K&N air intake, change the bearings (super worth and durable), engine mounts, sway bars, change the exhaust for a lighter one, change the headers, change the diffs or just their oil, change the injectors and coils, change the manifold, change the piston rings or just the pistons, change the engine bay, I mean you can do whatever you want BUT you seriously need to change everything in the engine if you change or swap any of it’s components for a smoother engine or it won’t be greatly tuned ans optimised, never forget to go to a tuning garage to computerized your changes for optimal performances and reliability. Always follow the manufacturer recommendations.

Thanks for the list Gumy. Would you possibly be able to give brand recommendations or libks to where I could research some of those parts more? Ive been digging through ECS Tunings catalouge as well as Turner Motorsports and havent really seen much of the more intricuit engine parts. However, I have found out that Turner will do custom differential builds so im thinking I might see if they could help me determine what to do there.

I would say look for supersprint exhaust or a magnaflow, K&N cold air intake, for the bearings you can look up to ECS bearings super durable and smooth, headers go for AP or autowerke, the diff optional but swap them for open or limited differentials (not an expert), injectors go for Autowerke, change for an open manifold for a bit of popping in the back, for the other else can’t tell you do researches on the web, find reviews I am more an E46 M3 and E39 540i and M5 expert

Ok perfect, thanks a lot gumy! I have a huge index of parts and where to get them that im trying to add to and expand. For much of the engine revamping I was thinking of trying to get ahold of an ESS TS3 kit that includes the 3.0L conversion with the larger injectors and all that. A lot of people seem to be super happy with it so that was where i was headed as far as power. Since it is AWD, the front axles and all the bushings in the area have me a bit concerned on their perdormance with higher power output, so do you happen to have any ideas around that? Beefier axles would be a nice addition too.

Yeah they do but it means a stronger chassis, more reliable and smoother on the road and it can even get you more grip in a certain way it changes the car alot don’t forget that they are the only thing that relies your chassis with the other part of your car. You can buy polyurethane bushings, ex: for the transmission it means smoother shifts, for the diff it gives more feels for cornering, improve suspension performance and power application (means superior service life compares to factory)

Buy polyurethane bushings ex: for the transmission it will give you smoother shifts, for the suspension you will feel more the cornering and sporty suspension you can buy ECS bushings they are more reliable than factory and gives you more feeling about the car.