leapingpoint

hi everyone,

i have a question on Sebring Quad Exhaust on W212...

i just installed a sebring exhaust made specifically for my 1.8 turbo W212. because i didn't like the 4 small round shape tips, i purchased rep AMG tips to replace them. however, because of size differences, it was difficult to weld all 4 tips onto the sebring exhaust for a perfect fit, especially that i have E63 AMG body kit too, so the auto shop decided to sealed off the two original tips on the sebring exhaust, and do a split on the rest of the two tips on the outside.

right now i've been testing the exhaust for 2 days and the sound is not that different from before - still very quiet... and i noticed that my RPM cannot exceed 6000RPM which is weird.

my question is, would this be because two of the exhaust tips are sealed off?
i've attached a photo below, any comments and inputs are greatly appreciated, thanks a lot in advance!