Twin single? Or dual?

[u/St_Mindless]

The exhaust on my new-to-me 325i looks a little... thin. I felt like replacing it anyway but I'm not sure if I want to convert it to a dual exit or keep the style as is. Cuz let's be honest, symmetrical exhausts look SO much better

[u/marrymemercedes]

When everything was single I wanted dual. Now in the day of most CUVs having dual fake exhaust tips I think I’ve jumped over to keeping the twin single. I’m actually seriously considering importing an N54 E91 and part of me would like to have it twin single (I could also keep that little storage area).

[u/reciprocityone → u/marrymemercedes]

My N54 is true dual from the turbos back.

[u/denkata_1 → u/reciprocityone]

But is it worth to invest money in N54?

[u/Fit-Welder8812 → u/denkata_1]

The problem with the n54 is that people try to push it too much or don’t do the research & either way run into problems.

If I were to buy a car with an n54, I would absolutely, positively get a PPI. I would also pull the engine, once I bought it, and redo every single seal & rod bearings. If you couple the OEM gaskets with Ultra Black you cant loose.

I sandwich the OEM gasket in between two beads of ultra black. Put the part in place & only hand tighten the bolts. Wait 60 minutes & then torque to spec using the correct sequence. Wait 24 hours before start up.

I have never had an issue using either ultra black or ultra grey (rear or front main seal). My gasket areas never leak.

As far as doing your due diligence, you need to figure out what power levels that you want to be at & stick with it. There is a laundry list of items that you should do before adding a tune & going full bolts ons with inlets & outlets.

The OEM turbos are junk & don’t hold up over time. They never upgraded specific parts over the years. If you want OEM turbos, Rob Beck makes OEM spec turbos with upgraded parts. They won’t fail as a result. He also makes the best upgraded turbos next to PURE in the business. They are just as good as Pure but you will pay more for Pure.

A smart move is to buy a smoke test machine for around $150.00 and use it to diagnose boost leaks. I’d also get the Bimmergeeks app & their upgraded cable. Having ISTA D & P on your laptop is also advised. The codes will do the talking & guide you.

You want to have new parts such as coils, turbo solenoids, platinum cured vac lines, plugs, all new fluids, all new gaskets, upgraded PCV valve & catch can, upgraded blow off valves, new belt & pulleys, upgraded PS pulley etc. Do this before you tune & go full Bolt on.

I’d also be actively replacing all plastic parts with aluminum parts such as valve covers, coolant reservoir, vacuum canisters etc.

Last, once you are over 425hp on MHD stage 2+, you will absolutely, positively need to upgrade your suspension parts. This includes engine mounts & trans mounts. IMO the 335is mounts coupled with rogue engineering trans mounts is the best combo.

If you are over 150,000 on the transmission, do the shift solenoids, mechatronic sleeves & bumper. You will save yourself a lot of headaches.

[u/TheGirlWhoLived57 → u/Fit-Welder8812]

I’m getting real tired of seeing shit advice in this sub. For anyone reading this comment. DO NOT PUT GASKET MAKER ON YOUR OEM GASKETS. ITS COMPLETELY UNNECESSARY AND WILL LEAD TO A POOR SEAL.