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Hey guys! I'm new here,I got my 05 Civic sedan LX last Nov. '04, I have about 10k miles on her as of today, the problem started when I replace my stock muffler with a universal muffler( the one that can be bought in ebay).
1.) I notice that she losses her speed, ex. when I'm driving at 45 mph I feel I was only at 25 to 30 mph and another, theres to much cabin noise.
2.) When I'm driving at above 65 mph, my steering wheel is starting to vibrates.

What is wrong with my car?

Pls. help me guys here, what should I do? Any suggestions will help.
Thanks.

 
Rep Power: 332

the steering wheel vibration is probably from bad alignment, not a muffler

 
Rep Power: 296

The speed thing is just on your head. Aftermarket mufflers are loud, be careful what you buy at eBay...you get what you pay for.
As for your steering vibration...may be an alignment issue, has nothing to do with your muffler.
Take your car for an alignment, rebalance your tires & check tire pressure.

 
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Thanks for your reply,but what about the noise in the cabin, how can I decrease it?

 
Rep Power: 296

You may have to buy a silencer to reduce the muffler noise...

 
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decreasing cabin noise is very tough to fix, but helpful things to decrease it are sound deadning such as (Dynamat, or Fatmat) check out the forums there are many posts available.

 
Rep Power: 454

Alignments out of spec dont cause steering wheel vibrations at 65+ MPH. It is probably unbalanced tires.

 
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Thanks guys.