[MrDoctorProfessorBMW]

Hopefully you have some answers. I recently bought a 2007 335i and I've never owned a BMW before this. So, needless to say, I don't know anything about these vehicles. I've been looking at modifications and I have a few questions that you guys ( and gals) may be able to help with.
First, the car came with a few mods already installed, like a Turbosmart Kompact Plumb Back Kit, a VRSF charge pipe, JB+ piggyback tuner, and dual cone intakes.
I did a little research and I guess the TS Kompact plumpback kit can be used in the place of a charge pipe a BOV, right? I this why I don't hear the "STUSTUSTU" sound when I get on the throttle? These diverter valve things make it quieter? Is that the only benefit? lower noise?

Will this -----> : VRSF OEM Location High Flow Silicone Inlet Intake Kit N54
fit on my engine after the mods that are already on there? These go from the outlet of the turbo to the intake right? So, they're just a larger diameter hose and smoother internal finish for better airflow? Does it really add 30-40hp?

What about the VRSF cat-less downpipes? hp gains? ease of installation? time for install? tools needed?

As the car is now it already seems faster than it has any right to be. I can't imagine a car with double the power that this has.... Maybe I've never really had a car that was considered fast before and this is normal, idk...Any thoughts?

[n54victim]

Originally Posted by MrDoctorProfessorBMW

the TS Kompact plumpback kit can be used in the place of a charge pipe a BOV, right? I this why I don't hear the "STUSTUSTU" sound when I get on the throttle? These diverter valve things make it quieter? Is that the only benefit? lower noise?

In a car with a BOV the excess air is vented (blown off) to the atmosphere and this is the iconic “psssshhht” sound everyone loves. Now with a car equipped with a Diverter valve, the excess air rather than being vented is re-routed back into the intake tract which results in not as loud of sounds.
The "STUSTUSTU" sound is turbo flutter, which is the compressed air not finding a route out, though usually harmless, it could potentially not be good. (My understanding someone correct me if I'm wrong)

Originally Posted by MrDoctorProfessorBMW

Will this -----> : VRSF OEM Location High Flow Silicone Inlet Intake Kit N54
fit on my engine after the mods that are already on there?

Should fit as long as your inlet diameter match your turbo.

Originally Posted by MrDoctorProfessorBMW

As the car is now it already seems faster than it has any right to be. I can't imagine a car with double the power that this has.... Maybe I've never really had a car that was considered fast before and this is normal, idk...Any thoughts?

Its a quick car, especially for its era.

[lookalikehuuh]

That sound you are looking for is not actually a great thing for your turbos... As I understand it, its charged air that has nowhere to go since the throttle body has closed and pushes its way back thru the turbo. In theory this shortens the life of the turbos necessarily. These Mitsubishi turbos are unreliable enough especially when pushed hard with a tune/Piggy pack.

I would say don't worry about making a stupid sound that these cars are specifically designed to avoid with the factory diverter valves. The VRSF inlet you are looking at do not go from the turbo to the charge pipe, they go from the intake/filters to the turbo inlet. If you want more sound from the turbo then replace your upgraded DVs to a blow off valve.

Super high level overview of air flow, i didn't cover every connection or anything but just so you have an idea of how air flows:

Filter>intake tube>Inlet tube>Turbo>Outlet>intercooler>Chargepipe>throttle body>intake manifold>valves>BOOM!>exhaust

[lookalikehuuh]

Originally Posted by MrDoctorProfessorBMW

Will this -----> : VRSF OEM Location High Flow Silicone Inlet Intake Kit N54
fit on my engine after the mods that are already on there? These go from the outlet of the turbo to the intake right? So, they're just a larger diameter hose and smoother internal finish for better airflow? Does it really add 30-40hp?

What about the VRSF cat-less downpipes? hp gains? ease of installation? time for install? tools needed?

Catless DPs will definitely provide more horsepower and improve turbo spool times since there is much less restriction in the exhaust track. However, you will get a check engine code for catalytic converter efficiency. A tune like MHD will suppress the check engine light for the catalytic converter. The DPs also improve the exhaust sound as well.

Installation can be rough depending on how rusty your car is but totally possible in your driveway with some jackstands and basic hand tools.

[MrDoctorProfessorBMW]

Originally Posted by lookalikehuuh

Catless DPs will definitely provide more horsepower and improve turbo spool times since there is much less restriction in the exhaust track. However, you will get a check engine code for catalytic converter efficiency. A tune like MHD will suppress the check engine light for the catalytic converter. The DPs also improve the exhaust sound as well.

Installation can be rough depending on how rusty your car is but totally possible in your driveway with some jackstands and basic hand tools.

I have a jb4 not mhd, but may change that due to the cel. I have a thing about lights on the dash and won't be able to do anything but stare at it even if it isn't necessarily an issue. The car was previously owned by a BMW mechanic and is in immaculate condition, mechanically and aesthetically.
So, from what everyone's said the typical "JDM" turbo flutter isn't something I should be concerned with. The turbos are decently loud when under hard acceleration and I'm guessing the VRSF inlets and downpipes will change the subtle stock exhaust note to a more aggressive sound and increase the turbo's whistly bits noise level as well. I just wanna here some pssh pshh noises. The upgraded Kompact Plumb Back Valve kit are like double the cost of the metal charge pipe and BOV. Is is better or worse than a CP and BOV?

You guys probably get this particular annoying question a lot but could you give me an estimate on the power I'm probably making on the mods I have?
So far I have a Magnum FORCE Stage-2 Cold Air Intake System, a BMS Aluminum Replacement Charge Pipe Upgrade, a Kompact Plumb Back Valve kit, and a JB+ tuner. I don't know if there's anything else installed this is just the stuff I can see. I think the coolest thing the car came with are the Michelin pilot sports. They are apparently really good tires. I'm new to the platform and I don't know what else to do to the car. I want around 450 hp as my end goal, I don't wanna push it too hard.

[oVeRdOsE.]

the TS Kompact plumpback kit, is OEM +. So it does the same thing as original, but better residual boost since the diverter valve have spring and better hose ; silicon VS plastic.

I had this on a metal charge pipe, and I simply use a BOV 25mm and cap the other hole. I did not spend money on a new charge pipe to get a single BOV exit.

You wont have the stustustu on this kit or any BOV. If you want this sound you need a closed charge pipe and open intake filter, no blow off. I wont do it on a piggy back and stock turbos, but doable.

You have JB4 or JB+ ?, not the same. Also JB4 got revision. If you have gen5, keep it, no need to spend money to scrap it and buy an MHD license. However, if you want to keep it simple, I do believe a simple OTS MHD flash will be more reliable.

Downpipe are pain to install, it's easy, but time consuming since you dont have space. Standard tools for the downpipes, but Ill buy O2 sensor sockets. You can do it with a wrench, but again, no space to torque.

If you have JB+, I wont expect more than 30+ bhp over stock.
If you go full FBO with MHD OTS (and better with a custom tune) expect 450+ bhp if you max out these turbos on a budget. Go to the N54 section and see dyno sheets.


I suggest to search on this forums and youtube, your questions have been covered many many time, existing N54 on stock form are probably more rare than modded one.

[MrDoctorProfessorBMW]

Originally Posted by oVeRdOsE.

the TS Kompact plumpback kit, is OEM +. So it does the same thing as original, but better residual boost since the diverter valve have spring and better hose ; silicon VS plastic.

I had this on a metal charge pipe, and I simply use a BOV 25mm and cap the other hole. I did not spend money on a new charge pipe to get a single BOV exit.

You wont have the stustustu on this kit or any BOV. If you want this sound you need a closed charge pipe and open intake filter, no blow off. I wont do it on a piggy back and stock turbos, but doable.

You have JB4 or JB+ ?, not the same. Also JB4 got revision. If you have gen5, keep it, no need to spend money to scrap it and buy an MHD license. However, if you want to keep it simple, I do believe a simple OTS MHD flash will be more reliable.

Downpipe are pain to install, it's easy, but time consuming since you dont have space. Standard tools for the downpipes, but Ill buy O2 sensor sockets. You can do it with a wrench, but again, no space to torque.

If you have JB+, I wont expect more than 30+ bhp over stock.
If you go full FBO with MHD OTS (and better with a custom tune) expect 450+ bhp if you max out these turbos on a budget. Go to the N54 section and see dyno sheets.


I suggest to search on this forums and youtube, your questions have been covered many many time, existing N54 on stock form are probably more rare than modded one.

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Wow, now THAT'S an answer. Thank you for taking the time to reply and answer my annoying questions. how's the MDH ots tune for day to day driving? Would it be better to get a custom tune from a local shop? I bought the downpipes but have no room to install them as I dont have a garage anymore. I see that you said a parking lot and jack stands. How long should the install take doing it this way? I've watched install videos on yt but they always have a shop and a lift.

[oVeRdOsE.]

MHD is probably the most play and forget tune on the market.
You still can do some tweaking, but overall this is a very dailyable option.

no need to go custom with the mods you want.

Downpipes can take anywhere from 2h to 10h on a DIY with limited tools. Really depends how all the stuff is jammed, skills, tools you forget , etc.

took me 45 min only to cut the flange bolts to the mid pipe because bolts where round out and no space to get a grinder there. Had to drill 45° angle and increase the drill bit size to break the stud out without damaging the flanges.

[lookalikehuuh]

Originally Posted by MrDoctorProfessorBMW

The upgraded Kompact Plumb Back Valve kit are like double the cost of the metal charge pipe and BOV. Is is better or worse than a CP and BOV?

You guys probably get this particular annoying question a lot but could you give me an estimate on the power I'm probably making on the mods I have?

I would say that the CP and BOV are going to give you more sound vs the diverter valves since they are venting directly to atmosphere instead of venting into the intake tub itself like the diverters do currently.

If you are correct that you have just a JB+ (which is meh...btw) I wouldn't expect too much power over stock, maybe like 20-30HP over stock power, so maybe 300-310HP-ish to the wheels.

Just so we are clear, when you say you want 450HP are you talking wheel horsepower or crank HP? Because 450crank is doable with good condition stock turbos. 450 WHP is going to be pushing those stockers pretty hard and is probably going to require a custom tune+E85(upgraded fuel pump)+full Bolt On.