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6 cylinders have a particular rasp to them unfortunately, i found this on my 300zx you need lots of mufflers to knock the rasp back, if you want volume go up in size at the back of system and keep the front mufflers. Naturally Aspirated sound better with the back box not been straight through too. My recommendation get an R35 GTR centre muffler I had one on my v6 NA and it actually sounded good, build system off that In 3 inch add or subtract rear mufflers till it sounds how you want. You have Throttle bodies to do all the squawking anyway. Or chuck a turbo on it.

🙋‍♂️ this is me. Not very good with posting haha. Yes I’m super happy with minky. Such a clean clean k11. And Alex has been a huuuge help with sorting parts and helping get her to our place! have a few plans for her, but will see how things go.

This is a possibility that I have considered

If it's one particular frequency you want to eliminate you could do a heimholtz resonator/j-pipe thing. I think it moves the frequency up or down by an octave Calculators here: https://strikeengine.com/helmholtz-resonator-calculator-exhaust-j-pipe-length/ An example of one:

I have started dialling in fuel a bit better with 2 or 3 full throttle runs so far. No cam advance, just setting a baseline. The shape of the fuel map / power curve is absolutely hilarious when there is no cam advance. So the peak VE (105%) is at around 5500, secondary peak 7000rpm 103% so pretty good for the dunga stock cams and no cam timing adjustments yet. Gave it a run to 8300rpm. Good news is that as expected the bank to bank difference narrows down as rpm/throttle opening goes up. But. At 2000rpm full throttle, its only around 55% VE max. It can only half fill the cylinder, so it must be bouncing a big bunch of the air back out. Still sucks until around 4500rpm then starts to wake up. It's also quite gross coming just off idle, as I think it's gaining a huge amount of throttle area quite quickly. Possibly also because I've got a secondary air source that bypasses the throttles (PCV line and brake booster) so it does weird stuff where more air comes into the throttles, but then the reduced vacuum means less PCV. or something. Dunno. It's getting better but it's been the hardest motor to tune so far. I think mainly because the injector position sucks. Will definitely look at doing some explorative drilling on my old heads to see if I can mount the injectors further down. It will be interesting to see how the exhaust cam timing will like to be adjusted as well, as I've never played around with that before. This graph isnt suggestive of final powerband at all. I am just posting it because it's comical to see how much this engine sucks shit with fixed cam timing. I suspect that the home position of the cam is hugely far back, so it's working kinda like the atkinson cycle on the 1NZFXE. So its trying to reduce pumping losses as much as possible by having the cam intake timing incredibly delayed. People say that the Mark X gets exceptionally good fuel economy for a big barge, so this is probably one of its tricks. It's also probably why it cranks over fairly easily with 12:1 comp as well. I bet it would read surprisingly low on a compression test. The low end should jump up by heaps with even say 10-15 degrees of intake cam timing added.

Bahahahha that is the precursor to building shed number 3!

I would not enjoy that argument.... Aluminium is not a urethane bush so technically doesn't need voids, but the original bush was designed to flex, which aluminium doesn't. I would be inclined to fail it myself, while admiring the ingenuity. However a few wraps of self amalgating tape around the rack under the bush, removes play and does allow flex, also does covers the 'no heating or welding of components'. Not that i would ever suggest you do such a thing in the interim and fit the new bushes later.

I've always liked the sound of this, but its probably unbearably loud. Rice bubble tune and fancy g-bag probably add to the choiceness of the exhaust note.

Best of luck. I have no advice because I've only ever been 100% happy with an exhaust note once.... And it wasn't on my car - but I spent a long time trying to recreate it

That was my suggestion too, also to try BNT but be prepared to spend ages comparing it etc. Or turn a pair of shells from aluminium and solid mount the thing ha

Weird rules….. I mean, I get why it’s the rules and keeps the thread “pure”, but it’s weird’ cause it’s only on OS and only in one area….. and I’ve not got deletion rights so I can’t fix it when I forget/get carried away and screw up…. Grizzle over. I’ve always liked these 4WD Datsuns (even settle for some of the 2WD ones). ‘Cause they look nice and make great noises….. Tend to be ridiculous money and/or fall-apart rust here.

Had this for sale on trademe for ages with surprisingly little interest, I rode it to work a few times and decided it's too good to sell cheap just for the sake of getting rid of it So it gets to stay

noice, I was thinking about a new gun. What settings did you land on to dial it in?

No wof. No rego. No worries

^ we are on the same page here. The exhaust manifold I made for the 4g63t in the mx5 I stepped up the diameter of the head flange and start of the runners, and left the head stock size. So it has about a 3-4mm lip where the head is undersized from the flange of the turbo manifold. This may be a total waste of time or even counter productive, but the theory was to provide some anti reversion properties. Can always trim back the head, or fill the manifold if I need to I guess.

Might have to get a WoF on the Sierra sorted then....

Well that’s less than ideal. 38mm fuel pump took about an hour to get out of the 45mm hole in the tank and needed the melted plastic bits cut off with a hacksaw blade through the hole. I “disassembled” it with a hammer after realising the plug was melted into it and there was melted plastic allll through it. Good times. Bought it from a well known NZ parts place as a Siemens pump too.

So. Who's keen on a burgerfuel spitfire square May meet?

This In the case you describe.

Yeah im saying when you get to a point in cam size, no matter the size of the exhaust side on turbo is gonna be a bad day, in terms of boost threshold. rotarys are inefficient as shit so produce a lot of exhaust gas for the the power they make. so small exhaust side always a bad day

I thought I mentioned the tip Dia thing here but it may have been over on @yoeddynz thread. If that diesel audi is like my suv, it may have speakers in the exhaust to augment the sound.

Yeah I can see that. So did some top level science today. I put a spatula type thing over one of the muffler outlets. It cuts down the bassy noisy by heaps and the tone changes a fair bit. I'm thinking the secret sauce is probably to do with keeping the exhaust pipe diameter small, then just adding more pipes if you need more flow. Reason I think this, is most factory cars have small diameter pipes. Then when someone puts on a big bore exhaust, it gets a real deep tone. I think one component of the exhaust noise that you cant change is the frequency that relates to how many rpm you are doing x how many cylinders you have. But then secondary to that, I think the tips probably resonate at a frequency relating to cross sectional area. Some supporting evidence: Motorbikes usually have small dia pipes and sound great. Zonda has 4x smallish pipes and sounds incredible This other zonda has 4x smallish pipes and same deal Then here is a zonda with only 2 pipes, that sounds like absolute bucket of shit: (grading on a curve, for having started with one of the best sounding exhausts on the planet) Four small pipes:

It's not like in the UK where it depends on how much of the donor vehicle is used in the new build?

Thanks! Bush is with bnt who seemed to care /give a shit so I'll find out how they got on tomorrow /Monday

That's why the bigger cams need a bigger hot side on the turbo to gain the boost threshold back. Don't go crazy huge on the AR, but up the wheel size and good things can happen. (Within reason) Anecdote: Old mate with fd rally car thought he could run the same smallish g30 turbo on his bridge ported engine that he did on the stock port engine. It sagged the apex seals on the first dyno run, then he fits an egt gauge and understands why. The same gas flow reversion/ lack of scavenge that you'd get from a small turbo big cam combo.