Gibson Superflows

abhernan · May 17, 2001

I have a 97 Sierra Z71/5.7L and true duals? (2 cat converters) into one stock muffler. I want to put in two mufflers in place of the one, and have duals all the way out. I've been looking into the Gibson Superflows for this.

Does anybody have these, or have any opinions on these or other worthy contenders. I'm not too interested in a really loud sound, but rather a cool, low rumble, and of course, more horsepower. Approx how much more HP can I expect to see (feel) by putting in dual exhaust all the way out? Also, how much increase in HP would I see by dropping in a K&N filter?

Thanks, this is my first post here - great forum!

76BBSub · May 18, 2001

My neighbor had a Gibson system on his GMC, but it was an older (early 90's) truck. It sounded great, nice low rumble, not raspy, a bit loud maybe for a daily driver, but it didn't bother him at all. Not sure exactly which Gibson mufflers were on it, though.

The exhaust is probably worth about 20 HP or so, maybe a little more or a little less. I think you'll feel a difference in throttle response, the old "seat of the pants" difference. K&N isn't worth a whole lot down low where your engine is normally running, but doesn't hurt and is worth it for the price and 5-minute installation time. Maybe 5 HP? You can pretty much guarantee that you'll feel a difference with the exhaust, and the K&N is just icing on the cake.

You might also look into Walker or DynoMax mufflers, they both have some fairly quiet super turbo mufflers. I have DynoMax super turbos on my Suburban. They sound great, although they are louder than they'd be on your truck, since I have headers and no cat ('76).

Jeff

abhernan · May 18, 2001

On the dual exhaust, does it make a difference if I have the tips go out on both sides of the truck (behind the rear tires) or on just one side? I'm not interested in having them straight out the back.

Roofer · May 18, 2001

Quote: from abhernan on 2:26 pm on May 18, 2001
On the dual exhaust, does it make a difference if I have the tips go out on both sides of the truck (behind the rear tires) or on just one side? I'm not interested in having them straight out the back.

I would say that it doesn't make a difference. Personally I would rather have one out each side rather than both out one side. The early 90's half tons had two out the same side, if your curios on how it looks. Let us know what you decide.

Later

Colorado Z · May 24, 2001

Thanks Roofer. I don't know how soon I can do this, we're buying a house in a couple of months, and the wife would probably throw me out with the dog if I spent any $$ right now, but this is definitely one of my must-haves! When I do, I think I'll go out to both sides of the truck. Is this what's referred to as a cat-back system, since I will not be modifying the engine to cat section?