Stock catback restriction
Thread Starter
12 Second Club
Joined: Feb 2012
Posts: 419
Likes: 4
From: Long Beach, MS
Stock catback restriction Just wondering if I'm leaving a bunch on the table by running a stock cat-back on my car. My feeling is probably very little, but I want other opinions.
The car has long tubes and ory, hooked to the stock 2-3/4 i-pipe.
Now, I understand that as the exhaust gas cools it doesn't need as big of a pipe, so is about a 1/4 inch going to make that much of a difference from the i-pipe back? I know that the stock manifolds are a big restriction as is the stock y-pipe, just not sure about the rest.
The car has long tubes and ory, hooked to the stock 2-3/4 i-pipe.
Now, I understand that as the exhaust gas cools it doesn't need as big of a pipe, so is about a 1/4 inch going to make that much of a difference from the i-pipe back? I know that the stock manifolds are a big restriction as is the stock y-pipe, just not sure about the rest.
I don't recall or know of any hard data to prove if a 3" would benefit, especially if the engine is at or near stock. If it were me I'd keep the way it is unless other engine mods are planned. JMO.
Just wondering if I'm leaving a bunch on the table by running a stock cat-back on my car. My feeling is probably very little, but I want other opinions.
The car has long tubes and ory, hooked to the stock 2-3/4 i-pipe.
Now, I understand that as the exhaust gas cools it doesn't need as big of a pipe, so is about a 1/4 inch going to make that much of a difference from the i-pipe back? I know that the stock manifolds are a big restriction as is the stock y-pipe, just not sure about the rest.
The car has long tubes and ory, hooked to the stock 2-3/4 i-pipe.
Now, I understand that as the exhaust gas cools it doesn't need as big of a pipe, so is about a 1/4 inch going to make that much of a difference from the i-pipe back? I know that the stock manifolds are a big restriction as is the stock y-pipe, just not sure about the rest.
), everything I've read over the years points to a ~10 HP gain even on a stock LT1 (much more on highly modified), the stock muffler is full of baffles that are quite restrictive, I could tell a difference in power back in the day when I just had a flowmaster muffler installed. At a minimum, get at least a decent flowing muffler installed, if not a full cat back if you have any plans of adding more HP in the future. I have proof for my claims as well....read, 9HP dyno proven gain on a stock LT1 by installing the Magnaflow cat back:http://www.carsandparts.com/Articles...r-from-the-lt1
^It should also be noted that 9hp gain was on a car that already had a free flowing aftermarket muffler, the pipes are restrictive too.
Here, Gm high tech performance added 30rwhp with just a CAI, Magnaflow cat back, TB airfoil, and 160 thermostat.....no way just a CAI, airfoil, and 160 thermostat alone are adding 30RWHP.
http://www.gmhightechperformance.com.../photo_24.html
Here, GM high tech lists approximate HP gains for best LT1 bolt ons....they claim 15 RWHP for most cat-backs, also, a cutout should be considered, any noobs out there really should read this:
http://www.gmhightechperformance.com...g_radials.html
Last edited by ahritchie; Mar 5, 2014 at 10:59 AM.
Thread Starter
12 Second Club
Joined: Feb 2012
Posts: 419
Likes: 4
From: Long Beach, MS
Isn't the point of headers to remove the restriction of the exhaust manifolds?
the purpose was actually to replace the cracked manifold with something better, which it did, and it removed the restriction of the manifolds and the stock y-pipe.
The stock exhaust IS restrictive (the village troll should know better ), everything I've read over the years points to a ~10 HP gain even on a stock LT1 (much more on highly modified), the stock muffler is full of baffles that are quite restrictive, I could tell a difference in power back in the day when I just had a flowmaster muffler installed. At a minimum, get at least a decent flowing muffler installed, if not a full cat back if you have any plans of adding more HP in the future. I have proof for my claims as well....read, 9HP dyno proven gain on a stock LT1 by installing the Magnaflow cat back:
http://www.carsandparts.com/Articles...r-from-the-lt1
^It should also be noted that 9hp gain was on a car that already had a free flowing aftermarket muffler, the pipes are restrictive too.
Here, Gm high tech performance added 30rwhp with just a CAI, Magnaflow cat back, TB airfoil, and 160 thermostat.....no way just a CAI, airfoil, and 160 thermostat alone are adding 30RWHP.
http://www.gmhightechperformance.com.../photo_24.html
Here, GM high tech lists approximate HP gains for best LT1 bolt ons....they claim 15 RWHP for most cat-backs, also, a cutout should be considered, any noobs out there really should read this:
http://www.gmhightechperformance.com...g_radials.html
), everything I've read over the years points to a ~10 HP gain even on a stock LT1 (much more on highly modified), the stock muffler is full of baffles that are quite restrictive, I could tell a difference in power back in the day when I just had a flowmaster muffler installed. At a minimum, get at least a decent flowing muffler installed, if not a full cat back if you have any plans of adding more HP in the future. I have proof for my claims as well....read, 9HP dyno proven gain on a stock LT1 by installing the Magnaflow cat back:http://www.carsandparts.com/Articles...r-from-the-lt1
^It should also be noted that 9hp gain was on a car that already had a free flowing aftermarket muffler, the pipes are restrictive too.
Here, Gm high tech performance added 30rwhp with just a CAI, Magnaflow cat back, TB airfoil, and 160 thermostat.....no way just a CAI, airfoil, and 160 thermostat alone are adding 30RWHP.
http://www.gmhightechperformance.com.../photo_24.html
Here, GM high tech lists approximate HP gains for best LT1 bolt ons....they claim 15 RWHP for most cat-backs, also, a cutout should be considered, any noobs out there really should read this:
http://www.gmhightechperformance.com...g_radials.html
... as I don't want to dump $500 on a catback right now.
But isn't the most restrictive part of the factory exhaust the stock y-pipe, followed by the manifolds?
Isn't the point of headers to remove the restriction of the exhaust manifolds?
the purpose was actually to replace the cracked manifold with something better, which it did, and it removed the restriction of the manifolds and the stock y-pipe.
Interesting. I may have to start looking at getting a magnaflow cat back. What I don't want is loud. It sounds pretty good the way it is. It may just stay the way it is for a while though as I don't want to dump $500 on a catback right now.
Isn't the point of headers to remove the restriction of the exhaust manifolds?
the purpose was actually to replace the cracked manifold with something better, which it did, and it removed the restriction of the manifolds and the stock y-pipe.
Interesting. I may have to start looking at getting a magnaflow cat back. What I don't want is loud. It sounds pretty good the way it is. It may just stay the way it is for a while though as I don't want to dump $500 on a catback right now.
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