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Old 08-08-2006, 02:15 PM   #1
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Just put new Beldin wires, Delco 41-932 plugs, 180 Ts, 2.7" pulley, and synthetic oil in my Park Ave.

What are the recommendations for exhaust work? It is bone stock from the manis to the muffler tip...I have heard Ported manis, high flow cat, and res. delete...What other brands or ideas are out there? Is the 94-95 down pipe in need of expansion? Thanks for the help....
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Old 08-08-2006, 02:21 PM   #2
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The general concensus here (with some offering different opinions) is that you will get the most bang for your buck with just a hi-flow Cat (Magnaflow recommended) and ported manifolds. The exhaust pipe and muffler itself are already hi-flow and stainless to boot. Most don't bother with the down pipe unless they've done serious top-end flow improvements and there are many here that feel the resonator delete is not only a waste of time, but that the sound you get is less-than-desireable.

Bill Wren even added a resonator for improved sound.
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Old 08-08-2006, 02:28 PM   #3
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Park of the charm of the Park Ave is the low quite exhaust. Maybe I will keep my res. How are the Series I manifolds compared to the Series II manis? I have a power log on the front of my series II, it seems to have helped a lot. The Series I manis look pretty good compared to the Series II on my GTP.

Also, is there a U-bend on the 94-95'*? I thought that I heard there was not (haven't had it on a lift yet either)...thanks,
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Old 08-08-2006, 02:52 PM   #4
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There are no U-bends on ANY H bodies. Never were. That'* a W body thing.

The S1 manifolds are superior to the S2, but are pretty much a self-port thing. You need to weld the outside of the flange to the runners (a little at a time with cooling in between to keep the flange from warping), then port the living snot out of the inner factory weld.

There are pics of mine if you do a search on 'holy exhaust cracks batman'. You'll find cracks on yours, too. I've not seen an un-cracked set yet.

I agree that a high-flow cat ($60 or so) and PEM'* are the best thing you can do for the S1. If my downpipe is a restriction, I'll be surprised.
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Old 08-08-2006, 03:00 PM   #5
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What is your new downpipe compared to your stock one? Were there cracks in the cross pipe too (connecting your front and rears)?
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Old 08-08-2006, 05:26 PM   #6
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I'm flowing more through my top end than any other S1 L67 out there, and I have a stock DP.

I found no cracks on the crossover, but did on both the front and rear manifolds. The temp/heat cycling is more severe on the mani'* than the crossover.

Keep in mind that my DIY ceramic coating works VERY well, and should help prevent the massive swing in temp cycles (slow down the cooldown in winter) that is probably the major cause of the cracks. Exhaust manifold gaskets (there are none from the factory) will also help prevent them from flexing and cracking.
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Old 08-18-2006, 06:17 PM   #7
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If I go with a high flow cat, what are the diameters on the in and the out? is it 2.25" all the way, or 2.5" Thanks for the help...
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Old 08-18-2006, 08:10 PM   #8
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It should be 2.5" in and out for the cat. You MAY have a rear O2 sensor on the Park Ave. Buick changed to OBD2 a year earlier than Pontiac on SOME models.
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Old 08-19-2006, 09:17 PM   #9
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It'* an OBD-II plug but OBD-I...from the scan tool that I borrowed...2.5, possible O2 sensor, thanks,
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Old 08-19-2006, 09:30 PM   #10
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One ? -Why only a 2.7" pulley? That'* practically no gain. Maybe 5-8 HP I'm guessing. if you have a CAI, and are doing a HF cat and possibly more exhaust work I definitely would've gone with a 2.5" or 2.55" (92-93 stock pulley) at the biggest.
My opinion, but then when seeing you're location I think you may have been right to go only to a 2.7" because of the altitude.
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