Question is this - I used to have radius pipes that were wide open (and ear splitting loud).
First, franco will have the polish decoder posted next so you can understand what I said. However, you said, 'ear splitting' so here are little clues to tuning things and understanding, flow, chemical reaction, speed of the event.
1. Flow: One is quiet, the other is loud. One restricts the noise, the other does not. One fills up a better cylinder charge-(loud), the other does not. These are a few differences of those changes to the pipe swap.
2. Chemical Reaction: One slows the air flow and the spent reversion, or, 'for every action out the port, there is a reaction back into the exhaust port = Backpressure.' Loud, that flow still says heat moves faster, so when loud is running, the [spent charge] flows faster out the port with less restriction. Again, the slow reversed also with the spent backed up. A fired off mix, mixed with fresh. That flow out the exhaust also sets the chemical reaction of more gas in the [newly charge] chamber, because the loud moved the fastest out; cleaned the chamber better; let in more fresh air; more oxygen-wink-wink! Look at the 2 chemical reactions of how much heat did you make: is HP. Slow and quiet makes less HP than loud.
3. Speed In-Speed Out: This is the exact same engine, same carb setting. All we are doing is holding a more/less restricted pipe; walking up to the exhaust ports; here comes quiet and think of how 'fast' that bubble comes out the port? All we did was change a pipe. The only thing I see happening is a speed of who leaves faster? With the less restricted flow, I have more gas with the exact same vacuum draw. How? When the exhaust closes, there is this term, 'overlap' where both valves are open and the chamber is cleaned of the spent charge this way. But if you pack too much and slow that flow, you chop down on the spent with the exhaust, not chop on half spent/half clean charge, man are you holding the ideal exhaust pipe. That says on intake; no carb change; same fuel content; same chemical to air is the same dose in the cylinder. Agreed? All I see now is the exhaust valve is timed to the same opening, right? The heat is speed out the port, yes? The unspent lowered the heat mixed with the fresh, no? The quiet keeps more mixed/spent air/unspent gas back up the reversion, yes? The quiet slows the bike down is a pipe change only. The loud is the better filled cylinder chamber and that is the difference, no carb mod enters the picture, but speed does.
The bike still has get up and go from a dead stop, it pulls hard thru the gears.
Answer. My take is speed: you pushing so hard out the pipe, we still have the same engine pushing that same feel. Look how the bike takes off from a dead stop. That is one fuel circuit to the next as in all 3 run up in a linear way and never shut off. Speed showed it still has the getup and go no carb change needed if anything it's rich so no harm no foul. And I mean it has to foul plugs rich. You show a white tip on the plug, that is not rich but, man that looks good. However, you need to look deeper to read a plug. Make sense now?
BUT - it seems sluggish at mid range, like 3rd gear and 2200rpm and you twist the throttle without downshifting. With the old exhaust, it used to have torque and pull hard, but now its a long slow climb to higher rpm's.
It has to explain itself so simply. Each step shows how the other step stepped, you step back or forward with the abstract. How simple was the pressure is pushing back in that chemical reaction in a slow rpm situation or fast. It still says, no matter the move, for every reaction, the spent is going to follow each stroke is pick an rpm. See, the action never stops but is linear at that exhaust port too. The bike is running with the quiet pipe and she cannot push out all that spent as fast as if slow in rpm too. That's the compromise, is the push back in. It is more how quiet works and said performance. Loud is the open door so it's going to have a more powerful charge and that means torque. It sped up faster with more heat to convert. The quiet is there with that for every mix, one is more powerful if loud. And every constant fuel to air mix into that chamber is a constant. It is about to show itself. Which intern shows the pipe change.
Is this due to it needing carb work to match the backpressure of the exhaust?
There is this simple yet very explainable way to say backpressure and see it. This is where the concept begins, you lay out the abstract from there. An engine without a pipe says, how did that bike run both ways no jetting needed? That engine is tuned, period. What happens next is: flow is [for every action] a problem; the chemical reaction is next; the speed out the tailpipe are 3 bandits like: fuel/spark/compression and that balance factor. I'm old so I may be missing one or it's so absolute like sparky and his buddies.
What is the pressure in the garage, on the tools, up the pipe, in the chamber, the bike is not running in the garage? 14.7psi.
What is the pressure trying to get back in at the end of the pipe we start the engine? 14.7psi.
What is the pressure inside the normally aspirated cylinder chamber> right before compression? 14.7psi
What is the answer, you cannot create or destroy the bubble. All you did was; kinetically compress it; chemically heated it; caused a bubble to expand robustly, and it went right back to? 14.7psi.
What is the chemical reaction of a spent vs. clean mixed fuel to air; and that air to fuel ratio is the x-ray inside that bubble; and the bubble you captured inside that chamber you are looking at is? 14.7psi.
What is the speed; no matter the speed in; is the cylinder chamber filled with; before compression happens? 14.7psi.
What is the first tuning number does a tuner tune off of, and finds the perfect AFR mix to that certain engine? 14.7psi: {ideal (stoic) emissions turns to harmless vapor, correct?]
What is the Penultimate number a turbo or blower engine is creating over a N/A engine? It has to hold in a certain number first, before the boost gauge shows a boost off of over? 14.7psi (1 atmosphere)
I am totally dumb when it comes to carbs, jetting etc. Is there just an OEM spec I can get the carb rebuilt to and it should work fine because of OEM exhaust?
No you're not totally out of the loop: it's boring theory you have to work out. You need to watch the bike talk to you first. The concept is this Penultimate number and it's called 14.7psi. The rest is using the [polish conversion] abstract to explain it. There is no book to explain this so you need to see the 'speed.' Does my bike start right up and idle? Yes. That means a clean carb and all 3 circuits are working and open. How much cleaner is that if gas is a detergent and it's cleaning it chemically. Kind of makes sense, right?
Shift down one to remove the mid-range lag. This spins the engine up and out the ass comes the bubble. Takes a Man to ride a stock bike and know a performance bike is better performing. Takes a Man to keep the stock pipes on and knows there is still the same HP on tap. Takes time for the [HP] to sneak up on you is all. That's the change up unless someone can explain it better from hear is show me the spark plugs.
I told you so. Did I not say do the work? I'm going to go cook my engine and check my plugs later. No you're not. Scared means, 'I'll check later.' Undumb means I look now and then say, 'I was scared for nothing.'
