If you are using it to poodle around estate to avoid antisocial noise then you're probably doing a good thing for social reasons. At low rpm a physical restriction in the system has good effect on noise. But if you put your foot down and essentially you have a blockage in the system then the gas flow is restricted, power is reduced and the overall strain on the engine components can be increased.
Note, diameter of pipe is not all, the velocity of gas flow is key to success, read - http://www.gomog.com/allmorgan/exhaustbackpressure.html
It is near impossible to judge the effect on the above parameters from aftermarket car exhaust equipment manufacturers because they rarely have any meaningful test data. It is a totally unrestricted free for all market largely full of misleading adverts and bullshit.
The law simply states that it is illegal to change your exhaust to one that is louder than the manufacturers original kit, and the onerous is on you the consumer.
Luckily for us GTIR Pulsar import folk there is no test data available and as such only need to comply with IVA import rules. I think it is 102dBA static position noise measured at 1 metre at 3/4s rpm. Simply put this is loud, and a UK Sunny will of been about 90dBA to pass UK rules. 10dBA quieter is a lot quieter...
Some police have no idea or don't care what the noise rules are, they can simply issue a Section 59 notice which you cannot appeal on site. It's a licence to print money and stop dickheads screaming through esates.
Some innocent people in import cars get caught up because some police take offence to some cars.
Think about it, you drive slowly through an esate in a pulsar or an American car of the same noise level, who is gonna get the Sec59 tickets from the police for noise? Very expensive to fight Sec59 in court, you'd probably win but, it is far cheaper to get a quieter exhaust than to fight the powers that be...
When aftermarket exhaust people are asked they usually say "every car & engine ever produced is slightly different and therefore we don't test anything properly because you cannot copy and paste the test results from one car to the next..."
Well that is total bullshit, they don't do it because proper testing is expensive. FYI in the power and construction industry, i.e. diesel generators, power stations, turbines, diggers etc, it is totally regulated (ISO/BS/EN/EU/EEC/DIN tested) and the exhaust gas flow, silencers and noise data is accurate and works, and is interchangeable across manufacturers.
I've never seen Armytrix before but take for example someone similar:
These are advertising an exhaust that is 'incredible loud!', probably very expensive and they probably don't have any meaningful bhp test data. Would you put an unregulated and untested exhaust on your $100,000 car? Yes of course you would, just in the same way we put mongoose on GTIRs, it's all relative and good fun pub talk...
The Fi youtube video seems to demonstrate noise test data and to the untrained eye I can see why people feel like it makes sense, but it is nonsense. Why?
Well first off the sound level meter (Type 2) they use is £16 on ebay:
The one I use costs £5,000 and measures full frequency response data. This is overkill for trackdays etc but if you are going to publish 'test data' then you probably want to spend a few hundred £££s on some proper (Type 1) noise equipment.
Also in the video they state dB values, well they don't understand what a dB is. Decibels need to have more parameters attached to them. dB 'A', 'C' or 'Z' is common and must be quantified by a distance too. Think if a car company said we can do 27MP... Well MP what? MPG or MPH?
The A, C, Z is a frequency weighting. Humans hear in 'A' weighting and dBA is what trackdays reference. Trackdays also reference a distance of 0.5m or 1m from exhaust at 3/4s rpm. Typically from 98 - 105dBA, some also have driveby levels.
Personally I would actually consider using a £16 one if you are simply curious before a trackday. If it left the factory 'calibrated' properly (most do) then worst case Type 2 might be 3dBA away from Type 1 measurement. Set it to dBA, fast, max hold, and give it a blast at what ever you need distancewise/rpm for your track day.
My car with full mongoose was 104dBA at 0.5m 5625rpm. I put a 500mm long 250mm oval simons silencer in the system and it is now 90dBA. 14dBA drop is hugely quieter and the gas flow will be pretty much the same because the cross sectional free area through it is the same.
Back to above Fi exhaust company - "Frequency Intelligent Valvetronic Exhaust System technology offers our cutting-edge intelligent ECU exhaust control valve, with an emphasis on the optimization of both acoustics and performance."
In summary they don't seem to have useful noise data and i doubt there's dynomometer test results. Those readings in the video I reckon are dBC and about 2m from exhaust.
Reality they have removed some silencers and got a black box to open the valves at a single preset rpm to completely bypass the tiny silencers. I doubt they will pass any UK track day noise levels and the police could Sec59 the shit out of them...
Sorry for the massive rant, lol, just flows out sometimes!
Does anyone have any pictures of the side exit exhausts that frequent the pulsars? Would love to see them not on a car?
Surely you can come out the turbo, turn 90 degrees and pass straight through a silencer (big as possible) and out the bumper... bit of good welding and you can make some small and quiet stuff.