So I have an 2005 that pops and backfires in the low to mid range, but pulls hard af after that. It’s like when you let the clutch out it stutters a little bit, coughs and pops then takes off. It’s got brand new plugs in it. And it’s perfect In neutral, or if you pull in the clutch when it starts to stutter. It’s only under load. Other then a yoshi slip on the bikes stock. I tried using seafoam and it just killed the plugs, which is why it’s now got a bn set in it.