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Discussion Starter #1
hi, I guess its all been on here before but here it is again, I have a 67 gto auto, pretty much stock, I had a new Gardner 2-1/4" system on car, no resonators and Gardners turbo mufflers, it was fine no drone, I still have system stored

but various friends said the gardner system is not mandrel bent, no X pipe, and mufflers are restrictive, and also 2-1/4" is too small, many said get a new 2.5 inch system mandrel bent with X pipe and straight thru mufflers for better sound and more power

ok bought the Pypes 2.5 inch system with X pipe, and 18 inch race pro mufflers, yes sounds a bit louder and tuffer, but really not sure I notice any real power difference, on dyno I guess it shows, but actual real time driving I didn't notice any great improvement
but what I do notice is it drones and its really annoying, and vibrates at the drone point,

I put up with it but eventually changed mufflers to 14 inch dynamax VT, yes it stoped drone but these mufflers sound very tame, and I think they have lost a bit of power compared to the race pros but nothing much, just don't like the dynamax vt sound

so today I installed magnaflow 18 inch 8 x 5 mufflers, no difference same as race pros they drone too, so now I am thinking after all this wasted money and time I might even just put the Gardner system back on, but I am thinking after running the 2.5 X pipe system for the last year or so I might notice the drop in power going back to the basic Gardner system

at this point its either back to Gardner 2-1/4" but that just feels like I am going backwards or put the whimpy dynamax vt's back on the pypes system

has anyone any ideas on how I can keep the pypes system, race pro or magnaflow mufflers don't matter as I have both, but eliminate this drone ? thanks
 

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hi, I guess its all been on here before but here it is again, I have a 67 gto auto, pretty much stock, I had a new Gardner 2-1/4" system on car, no resonators and Gardners turbo mufflers, it was fine no drone, I still have system stored

but various friends said the gardner system is not mandrel bent, no X pipe, and mufflers are restrictive, and also 2-1/4" is too small, many said get a new 2.5 inch system mandrel bent with X pipe and straight thru mufflers for better sound and more power

ok bought the Pypes 2.5 inch system with X pipe, and 18 inch race pro mufflers, yes sounds a bit louder and tuffer, but really not sure I notice any real power difference, on dyno I guess it shows, but actual real time driving I didn't notice any great improvement
but what I do notice is it drones and its really annoying, and vibrates at the drone point,

I put up with it but eventually changed mufflers to 14 inch dynamax VT, yes it stoped drone but these mufflers sound very tame, and I think they have lost a bit of power compared to the race pros but nothing much, just don't like the dynamax vt sound

so today I installed magnaflow 18 inch 8 x 5 mufflers, no difference same as race pros they drone too, so now I am thinking after all this wasted money and time I might even just put the Gardner system back on, but I am thinking after running the 2.5 X pipe system for the last year or so I might notice the drop in power going back to the basic Gardner system

at this point its either back to Gardner 2-1/4" but that just feels like I am going backwards or put the whimpy dynamax vt's back on the pypes system

has anyone any ideas on how I can keep the pypes system, race pro or magnaflow mufflers don't matter as I have both, but eliminate this drone ? thanks
My '70 has the 2.5" Pypes Pro Street system with X pipe when I purchased the car. Whomever installed the X pipe installed it too close to the Transmission pan. It had a noticeable unsightly sag and would scrape occasionally on low clearance. It also had a drone 35-40mph. I had the X pipe removed and ran straight pipe. The sound is more aggressive and a little louder and the done left. It is louder when driving at steady speeds but there is no drone. My cam is more pronounced. Overall I like the sound of it and get many asking me about the cam and sound system. If you like the pypes sound try removing the X pipe and see if the done disappears?
 

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Discussion Starter #3
I was suggested to me by the muffler shop to remove x pipe, but he also said it will be loud, I don't want it loud in the cabin its a family cruiser not drag racer , I don't think I would like it louder than it already is so I guess x pipe stays, or I go back to the gardner system its no x pipe but does have the more restrictive turbo mufflers so I would assume I loose power but maybe that's going to be the only option to rid this drone
 

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I was suggested to me by the muffler shop to remove x pipe, but he also said it will be loud, I don't want it loud in the cabin its a family cruiser not drag racer , I don't think I would like it louder than it already is so I guess x pipe stays, or I go back to the gardner system its no x pipe but does have the more restrictive turbo mufflers so I would assume I loose power but maybe that's going to be the only option to rid this drone
It's not that loud in the cabin it's annoying it's loud enough to let me know it's aggressive. The drone was more annoying than the added noise level.
 

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When I bought my '67 it had a crossover with Magnaflows and it was just loud and didn't have that classic GTO sound.
I replaced the whole system with the Gardner 2 1/2" with the resonators and it is very quiet at cruising speed but has a good rumble when the secondaries open up.
That X pipe automatic transmission heater is a stupid design and I don't know why anyone would put that on their car.
The car wasn't designed with a crossover and if it was me I would put the Gardner system back on and call it done.
YMMV
 
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