I used to ru between 180-190. After I put the cat back on I now run between 210-230.
Has anyone ever had this problem?
I think I have too much engine for this exhaust. I used to have a 3" edelbrock muffler right off of my y pipe and it ran great with no heating up problems.

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forgot

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350 4 bolt 30 over 11-1 comp, edelbrock rpm heads, 250 260 dur@50 .533 .555 lift,holley intake 650dp, holley strip ann. ign coil and dist. Edelbrock headers and cat back. th 350 with 3200 stall. Rearend soon to come

 

Sorry forgot a few other details that might be of some help in my setup

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350 4 bolt 30 over 11-1 comp, edelbrock rpm heads, Lunati 1.5 roller rockers,Wolverine Solid cam 250 260 dur@50 .533 .555 lift,holley intake 650dp, holley blue pump and reg, holley strip ann. ign coil and dist.
Accel 300 plu wires, Edelbrock headers and cat back. th 350 with 3200 stall. Dual fans and three core rad, Rearend soon to come posi and 4.10 gears

 

Could be that you do have a little too much engine for the exhaust, but actually, since you have moved the muffler further down stream, there is less backpressure. I am running a very similar engine, and when I had a single 3in catback on it, it was fine. I would look into the car detonating (that is a whole lot of compression if you are running pump gas) also, it is getting hotter outside, is it possible that this is a coincidence?

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Black 89 IROC...355, Solid Crower Cam, TFS heads. 12.0 @ 120.3mph with a 1.9 60ft...all motor

 

what exhuast are you running now? What temp does your car run at?

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84 Z28 t-tops ,350 4 bolt 30 over 11-1 comp, edelbrock rpm heads, Lunati 1.5 roller rockers,Wolverine Solid cam 250 260 dur@50 .533 .555 lift,holley intake 650dp, holley blue pump and reg, holley strip ann. ign coil and dist.
Accel 300 plus wires,Solid motor mounts, Edelbrock headers and cat back. th 350 with 3200 stall. Dual fans and three core rad, Rearend soon to come posi and 4.10 gears