Drilling that endcap isn't gonna affect the popping either way...What that does is deepen the tone of the exhaust, making it sound less "blatty"...
The popping you're hearintg on decel is from the PAIR valve system on the bike...PAIR valve system is an emissions control setup similar to the air pumps that used to be installed in cars in the late 70's/early 80's....It's a vacuum operated solenoid that on decelleration, injects fresh air into the exhaust ports in the heads to dilute the emissions coming out the pipes...It's been making the noises all along, but with the pipes as quiet as they were stock, you just couldn't hear it working...Most guys get a set of block-off plates (under $20 a set) and remove the system...Gets rid of the popping, and also with that crap gone, it frees up space to do the valve adjustment....
Also some folks think they can get away with just plugging the hose for the PAIR solenoid at the airbox, but that's just an invite for more problems down the road...Condensation will build up in the hoses and leak water into the exhaust, and rust out the pipes...There's a thread here in the archives of a member that had that very thing happen to his aftermarket exhaust...Bto just do it right the first time...
The popping you're hearintg on decel is from the PAIR valve system on the bike...PAIR valve system is an emissions control setup similar to the air pumps that used to be installed in cars in the late 70's/early 80's....It's a vacuum operated solenoid that on decelleration, injects fresh air into the exhaust ports in the heads to dilute the emissions coming out the pipes...It's been making the noises all along, but with the pipes as quiet as they were stock, you just couldn't hear it working...Most guys get a set of block-off plates (under $20 a set) and remove the system...Gets rid of the popping, and also with that crap gone, it frees up space to do the valve adjustment....
Also some folks think they can get away with just plugging the hose for the PAIR solenoid at the airbox, but that's just an invite for more problems down the road...Condensation will build up in the hoses and leak water into the exhaust, and rust out the pipes...There's a thread here in the archives of a member that had that very thing happen to his aftermarket exhaust...Bto just do it right the first time...
