[CSM3]

Hey guys,

I have been thinking of doing a project exhaust which in my opinion, and the various people i have spoken to, makes sense for our N55 engines. The test car would be mine, and if we go ahead with the project it will be done sometime mid to end january.

After some readings, i learnt that the best exhaust for a turbo car would be the most free flowing exhaust you can get, however the problem tht ensues would be more low end lag, and less low end torque. I don't think this will limit the car's potential in anyway because we have a good amount of torque from the N55s.

That aside my plan is basically to follow HPF's exhaust system. Except that im looking to install a muffler in the middle of the exhaust system, and like the conventional mufflers near the tips. The muffler i plan to use is almost straight-through like, so it should not cause too much back pressure. The good thing though is that i definitely want some back pressure, just so the low end torque isn't sacrificed too much.

This is the tentative design we have (courtesy of dave96dcm who will be executing the weldings and install).

From my AR Catless DP, i will connect two 2.5 inch pipes (Total cross section of 9.8), that joins in to ONE 3.5 inch pipe (9.62 cross section). Following the 3.5 inch pipe will be a 3.5'' mid exhaust muffler (Just to quiet things down and reduce droning), that will exit in to two 3" pipes leading to the tips.

Let me know what you guys think, btw i ain't a family guy yet, so i don't mind the fact that this might be a really loud exhaust! But i think my car looks the part! so i think it should sound the part!

[Slops]

My vote is a single pipe from the turbo to right before the rear axle where you split them to the duel mufflers and out back!

[mashimarho]

I'm doing a project myself.... M3 quads :]

[CSM3]

Originally Posted by Sloppy

My vote is a single pipe from the turbo to right before the rear axle where you split them to the duel mufflers and out back!

that would require a new dp! not really worth the $$$

[CSM3]

Originally Posted by mashimarho

I'm doing a project myself.... M3 quads :]

nice! be sure to post pics when ur done!

[Evooooo]

Your not going to lose low end grunt @ all. Turbos need to breathe, the more free flowing the easier the turbo spools the more tq n power it makes. Soo open that bitch up n leave it as free flowing as possible.

[Slops]

Originally Posted by bimmer35

that would require a new dp! not really worth the $$$

If its not a turbo back then it's not a full exhaust in my opinion. Do it right the first time.

[Abear]

You wouldnt have to get a new DP, just cut yours and weld a new pipe to it. Of course, the AR pipe is more oval than round, so it might be difficult, but if you cut it at the weld right before where the bolt mounts the pipe, you could just find a pipe to weld right there and have a turbo-back exhaust. At least that way you could run one big pipe instead of 2 smaller pipes.

If I had the funds and the time to attempt this, thats the way I would do it. I have berk DP that Im waiting on, but from the looks of it, it would be very easy to modify it and have a single 4" exhaust all the way back and then split in to 2 mufflers. Thats the way I would do it.

[CPWINCH]

there will be zero gains, you will still have the split at the dp which is a obstruction and might aswell split into two pipes. Only way you will have gains is if you buy the new downpipe (rsi?) and go single piple all the way from there and split it at the very end. Resonator on mid pipe and a nice muffler at the end.

[CSM3]

Originally Posted by Sloppy

If its not a turbo back then it's not a full exhaust in my opinion. Do it right the first time.

That's true, but the RSI isn't in my budget right now. Maybe i should hold off a little more or try the below. Thanks though.

Originally Posted by Abear

You wouldnt have to get a new DP, just cut yours and weld a new pipe to it. Of course, the AR pipe is more oval than round, so it might be difficult, but if you cut it at the weld right before where the bolt mounts the pipe, you could just find a pipe to weld right there and have a turbo-back exhaust. At least that way you could run one big pipe instead of 2 smaller pipes.

If I had the funds and the time to attempt this, thats the way I would do it. I have berk DP that Im waiting on, but from the looks of it, it would be very easy to modify it and have a single 4" exhaust all the way back and then split in to 2 mufflers. Thats the way I would do it.

This actually makes a lot of sense. Do you guys think i should just go straight through ALL the way instead of a mid pipe resonator?
Thanks!

Originally Posted by CPWINCH

there will be zero gains, you will still have the split at the dp which is a obstruction and might aswell split into two pipes. Only way you will have gains is if you buy the new downpipe (rsi?) and go single piple all the way from there and split it at the very end. Resonator on mid pipe and a nice muffler at the end.

what if i use the stock mufflers still, but one single piping all the way from the turbo?
Thanks!

[CSM3]

BTW, do you guys think i could go 4'' or should i just stay with 3.5 for the piping?

[CPWINCH]

Originally Posted by bimmer35

what if i use the stock mufflers still, but one single piping all the way from the turbo?
Thanks!

That would be sick. Honestly I think you should sell your dp and go the rsi route with a cutom mid pipe to whatever mufflers. with before and after dynos this could help other n55 owners to get the most power and youd be the first to do it. if you are gonna do a big project might aswell do it the best way possible you know?

[ciomas]

what if i use the stock mufflers still, but one single piping all the way from the turbo?
Thanks!

This is your best bet

[ciomas]

Originally Posted by CPWINCH

That would be sick. Honestly I think you should sell your dp and go the rsi route with a cutom mid pipe to whatever mufflers. with before and after dynos this could help other n55 owners to get the most power and youd be the first to do it. if you are gonna do a big project might aswell do it the best way possible you know?

+1

[CSM3]

Originally Posted by CPWINCH

That would be sick. Honestly I think you should sell your dp and go the rsi route with a cutom mid pipe to whatever mufflers. with before and after dynos this could help other n55 owners to get the most power and youd be the first to do it. if you are gonna do a big project might aswell do it the best way possible you know?

i totally agree, but i think i could do what the other guy said and just weld from my AR dp, by cutting of the split. Wouldn't that be just one huge 4" all the way from the turbo?

Damn i wish i could slap on the Remus quads, but thats really just a dream now. I might as well just use the stock exhaust first till i save up for more.

Plus the flap from the stock exhaust might help reduce drone considerably!?

PROBLEM. there is no 4WD dyno near me in Mass.
Only before and after times i can do is the 1/4 mile.

[CPWINCH]

Originally Posted by bimmer35

i totally agree, but i think i could do what the other guy said and just weld from my AR dp, by cutting of the split. Wouldn't that be just one huge 4" all the way from the turbo?

Damn i wish i could slap on the Remus quads, but thats really just a dream now. I might as well just use the stock exhaust first till i save up for more.

Plus the flap from the stock exhaust might help reduce drone considerably!?

PROBLEM. there is no 4WD dyno near me in Mass.
Only before and after times i can do is the 1/4 mile.

you could do that forsure but 4 inch is big and the problem is space if you can get that to fit that would be sick. I can guarentee you theres a 4wd dyno within atleast 2 hours away. I have the ar dp too and from what I remember it is ovalish so conecting a pipe would be weird. quarter is inconsistant and wont really show anything atleast do 60-130s but than u would have to buy a vbox lol

bad thing about welding it to the ar is you cant sell it after. When u go to sell your going to have to sell the whole kit

[CSM3]

Originally Posted by CPWINCH

you could do that forsure but 4 inch is big and the problem is space if you can get that to fit that would be sick. I can guarentee you theres a 4wd dyno within atleast 2 hours away. I have the ar dp too and from what I remember it is ovalish so conecting a pipe would be weird. quarter is inconsistant and wont really show anything atleast do 60-130s but than u would have to buy a vbox lol

bad thing about welding it to the ar is you cant sell it after. When u go to sell your going to have to sell the whole kit

Yeah, but im planning to keep this car for awhile, and im planning to have connectors throughout the exhaust so it shouldn't be too hard to sell.

Best part is that there are oval 4'' pipes, and the guy whose working on this with me knows where to get it from. So that might actually really work.

I tried searching for a AWD dyno around here and i couldnt find any? Do u know of one to recommend?

Will do some research and update u guys. Thanks for all the help!

[CPWINCH]

Originally Posted by bimmer35

Yeah, but im planning to keep this car for awhile, and im planning to have connectors throughout the exhaust so it shouldn't be too hard to sell.

Best part is that there are oval 4'' pipes, and the guy whose working on this with me knows where to get it from. So that might actually really work.

I tried searching for a AWD dyno around here and i couldnt find any? Do u know of one to recommend?

Will do some research and update u guys. Thanks for all the help!

nice man. get this thing started and show us a sketch before u start working. i wish i could help but im from california. go to ur regional forum and post asking for one.

[Slops]

Awesome keep us updated man!

[Abear]

Nice, thats what Im talking about! Everyone collaborating trying to help each other out! If I were you, and had a little extra money, I would just do a single 4" pipe all the way and then split to 2 mufflers. You could always go back and add a resonator later, it will have to be welded or clamped in either way. If you really wanted, and had the extra time, you could just sell your AR pipe and pick up a Berk, or just have a shop custom make one. But, since your guy knows where to find oval pipe, maybe he can just do it. Thing are beginning to come, what I like to call...gether!

[CSM3]

Originally Posted by CPWINCH

nice man. get this thing started and show us a sketch before u start working. i wish i could help but im from california. go to ur regional forum and post asking for one.

Yeah definitely, but will most likely be starting on this sometime in mid to end jan, as i will be going overseas for a month or so this winter.

Looking forward to it, and thanks for all the help guys!

[Slops]

Did you guys notice that the f30 comes with one single exhaust from the turbo and split at the back for duel exhausts???? I wanna see if I can just buy that exhaust and get somebody to make the single out catless dp for it