Exhaust mod opinions
08-06-2008, 04:18 PM
#1
Racer
Thread Starter
Exhaust mod opinions
My '03 has headers w/o pre-cats, stock main cats, and an exhaust I bought from Jeremy of IA, which is supposed to be a Fabspeed unit. To be honest it looks just like a TopSpeed unit or one of the ones available on eBay. Anyway, I L-O-V-E the sound of the thing and with the top down the resonance isn't bad at all, but with the top up it is. Also, the resonance is right at the "being-good-highway-cruising-speed" rpm range.
So I had a couple of ideas to cut down, or cut out, the resonance and I would like to hear opinions about how effective they might be. Below is a pic of the exhaust for reference.
Option 1) Modify the Fabspeed muffler design. Install an 1.5" cross tube in between the two chambers on this muffler, and add mounting studs to the top surfaces of the chambers so that the stock isolated mounting bar can be used for mounting this to the upper mount. Between the isolation offered by the stock mounting arrangement and the equalizing cross tube, most of the resonance may be removed. I have noticed that any muffler design which has been said to NOT resonate utilizes a either an equalizing tube or a head-to-head tube like the stock muffler. I am surmising that the purpose for this is to balance the flow and reduce standing waves. These modifications would address those same issues.
Option 2) Modify my still intact stock muffler. The PPBB stock muffler mod basically copies what the sport muffler does - dump a portion of the exhaust directly from the inlet flow into the out flow. There is another mod that describes dremmeling out about a 1" square opening in the stock muffler's through tube, just inboard of where the through tube is welded to the muffler body on each side. This dumps a portion of the inlet exhaust directly into the outer chamber, or just prior to exit, bypassing the first 2 chambers. I am told that if you remove the outlet cover and look back through the two ~ 1.3" outlet holes in the muffler, you can see through to the same inlet through tube. Could I not accomplish the same result by going through those openings with a 1" drill and drilling two 1" holes in the central area of the through tube? Would this not also allow a portion of inbound exhaust to escape directly into the outlet chamber?
Hearing opinons of anyone who has tried any of these mods, or that has knowledge of the exhaust would be appreciated before I start modifying anything.
So I had a couple of ideas to cut down, or cut out, the resonance and I would like to hear opinions about how effective they might be. Below is a pic of the exhaust for reference.
Option 1) Modify the Fabspeed muffler design. Install an 1.5" cross tube in between the two chambers on this muffler, and add mounting studs to the top surfaces of the chambers so that the stock isolated mounting bar can be used for mounting this to the upper mount. Between the isolation offered by the stock mounting arrangement and the equalizing cross tube, most of the resonance may be removed. I have noticed that any muffler design which has been said to NOT resonate utilizes a either an equalizing tube or a head-to-head tube like the stock muffler. I am surmising that the purpose for this is to balance the flow and reduce standing waves. These modifications would address those same issues.
Option 2) Modify my still intact stock muffler. The PPBB stock muffler mod basically copies what the sport muffler does - dump a portion of the exhaust directly from the inlet flow into the out flow. There is another mod that describes dremmeling out about a 1" square opening in the stock muffler's through tube, just inboard of where the through tube is welded to the muffler body on each side. This dumps a portion of the inlet exhaust directly into the outer chamber, or just prior to exit, bypassing the first 2 chambers. I am told that if you remove the outlet cover and look back through the two ~ 1.3" outlet holes in the muffler, you can see through to the same inlet through tube. Could I not accomplish the same result by going through those openings with a 1" drill and drilling two 1" holes in the central area of the through tube? Would this not also allow a portion of inbound exhaust to escape directly into the outlet chamber?
Hearing opinons of anyone who has tried any of these mods, or that has knowledge of the exhaust would be appreciated before I start modifying anything.
08-06-2008, 07:56 PM
#2
Instructor
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Option 1) Modify the Fabspeed muffler design. Install an 1.5" cross tube in between the two chambers on this muffler, and add mounting studs to the top surfaces of the chambers so that the stock isolated mounting bar can be used for mounting this to the upper mount. Between the isolation offered by the stock mounting arrangement and the equalizing cross tube, most of the resonance may be removed. I have noticed that any muffler design which has been said to NOT resonate utilizes a either an equalizing tube or a head-to-head tube like the stock muffler. I am surmising that the purpose for this is to balance the flow and reduce standing waves. These modifications would address those same issues.
Option 2) Modify my still intact stock muffler. The PPBB stock muffler mod basically copies what the sport muffler does - dump a portion of the exhaust directly from the inlet flow into the out flow. There is another mod that describes dremmeling out about a 1" square opening in the stock muffler's through tube, just inboard of where the through tube is welded to the muffler body on each side. This dumps a portion of the inlet exhaust directly into the outer chamber, or just prior to exit, bypassing the first 2 chambers.
08-13-2008, 05:02 PM
#3
Racer
Thread Starter
John, thanks for the reply for starters.
Listen, if I take the outlet tip off the stock muffler, and look back through the two outlet openings, I am told that I will beable to see the cross tube that you are dremmeling out near the inlets. If I go through these outlet holes and drill two 1" holes into that cross tube in this location (keeping them as far away from each other as possible within that center chamber) , would that not accomplish the same mod ? Seems like it would be easier to do.....
Listen, if I take the outlet tip off the stock muffler, and look back through the two outlet openings, I am told that I will beable to see the cross tube that you are dremmeling out near the inlets. If I go through these outlet holes and drill two 1" holes into that cross tube in this location (keeping them as far away from each other as possible within that center chamber) , would that not accomplish the same mod ? Seems like it would be easier to do.....
