I did the straight pipe conversion last summer. Sound-wise, it will be quite a bit louder, and yes, the quality does degrade. For me, it's a love/hate thing. It's throaty at low revs and during trailing throttle at high revs. Anywhere else tho, it's higher pitched and raspy.
Performance-wise, I felt a dip in mid-range power, but the top end improved, feels like the hp is higher at redline than at 6250rpm. This is for a standard 2.5l.
If you plan on headers, I DO NOT recommend the straight pipe. Got my MSDS on yesterday, it's SUPER LOUD, and sounds like butt. Yeah, it sounds mean, but not appealing to the senses at all (except at idle, "blurp blurp blurp", but that's it).
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'99 Cougar V6 5spd
