sonata owner

Hi all,

I have replaced spark plugs recently for my Sonata 99.

I bought NGK spark plugs at Napa, confirming Napa's database.
But the part number does not match exactly to the HMA web site
recommendation.

After the replacement, it seems that the engine is little bit louder
now. Is this normal?

What can make the engine louder?


A disturbed throttle cable adjustment?

Out of heat range spark plugs?

Or, the computer being turned off, it forgot my driving style and need
time to adjust?



Do I have to do additional things other than just replacing spark
plugs, such as cleaning throttle body?


Thanks,
Jae.