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My '04 has recently developed a rattle in one of the cats and when I bought it (2+ years ago), the PPI said that one of the header runners was dented. To solve, I pulled the trigger on a FVD Brombacher 200 cell cat and I plan to couple that to a set of 997S headers. Initial impressions are encouraging. The 997 headers look better than the pictures I had seen (I was a bit concerned about how free-flowing this design would be...)
The cats are truly fantastic, beautiful workmanship - really a pity they will be entirely out of sight! Anyway, I'll update this thread as I go.
Any suggestions on (reasonable) preventative maintenance to do while I'm in there? I have already ordered plugs as I've not done those yet.
I have those cats, your gonna love em. Lots of penetrating oil, spray drive, repeat. I'd recommend having a few spare exhaust/header nuts and bolts, I broke one without applying much force. I disconnected the O2 sensor plugs and lowered the old cats with the sensors attached. No need to remove the bumper.
Enjoy
I have the same cats. I needed spacers for both post cat O2 sensors to avoid CELs. No noticeable loss of torque, in fact my lap times improved on the track.
I have the same cats. I needed spacers for both post cat O2 sensors to avoid CELs. No noticeable loss of torque, in fact my lap times improved on the track.
Huh, I'd thought the 200 cell cats would be efficient enough not to trigger a CEL. Do you have the 100 cell cats perchance?
Which spacer did you use? I could just install a pair to preempt any issues.
Huh, I'd thought the 200 cell cats would be efficient enough not to trigger a CEL. Do you have the 100 cell cats perchance?
Which spacer did you use? I could just install a pair to preempt any issues.
200 Cell cats here. I found straight spacers on Amazon. You can easily monitor your O2 sensors with a durametric. I'd only use them if needed.
I'm currently hosing down the header bolts with Kroil nightly, planning to remove the headers this weekend. I'm aware that the header bolts are notorious for snapping upon removal and mine do seem rusty.
I'd like some advice on whether or not to use a 1/2" impact driver. Or attempt to turn the bolts manually? I guess the impact driver might shock the bolts loose before they can break ... but the impact driver might also be strong enough to snap the shaft.
Also, what about engine temperature? Should the engine be hot when I try this? Seems to me that the aluminum head might expand more than the bolts so perhaps they will be looser when the engine is hot?
From: Ephrata, PA, USA now. Originally from the UK
No biggy if the bolts break. Mine did when I removed the cats to do my plugs and sleeves. Even after an overnight soaking they snapped off. I simply replaced them with new bolts.
Very cool upgrade and while you are down there with the car on jack-stands, it may be good to check the condition of your motor mounts. With the bumper cover on it's easy to see the exhaust tips sag for worn/tired mounts. Anyway good-luck with those header-bolts and enjoy your upgrade, cheers...
An update on my winter project.
Even after extensive Kroil treatment, I found that every exhaust bolt I touched simply snapped with ridiculous ease, all the catalytic converter bolts and brackets, even the long bolts mounting the muffler to the bracket. I'm very sure that all the header bolts would have snapped and I don't fancy drilling them out even using the Stromski kit while lying on my back. So I cut scope and decided to leave my factory headers attached. The 997S headers will be on hold until I remove the engine - surely not too long till that happens . On a similar note, I broke off the oil filler tube but I'll use a 40mm silicone coupler to fix that, again until I remove the engine and can replace the stock one.
On the plus side, the rest of the project is going well.
- Spark plugs - fairly easy, though I can't see how you could change them with the mufflers in place as some apparently do (maybe I need Trump-sized hands?). #1 (rearmost, passenger side) was the worst as you don't have much room to work in. The old plugs look okay as regards deposits/discoloration. 50k miles of service if the records are correct so the electrodes are worn. Coil packs are 997 part number and also in good condition.
- Water pump and low temp thermostat. Easy replacement with the catalytic converters, rear bracket, bumper etc removed.
- Coolant flush. Thanks to Ahsai's procedure with the pressure flush, this was simple. There is a pic below of how I used a tire inflator in conjunction with one of the parts in the airlift system to make a tool I used to pressurize the coolant tank to 10 PSI. I flushed the system with water twice to remove all traces of the old coolant. Replaced with the vacuum Airlift device - amazing product!
- PSE! My car was not factory equipped with this, but I found a set on Ebay. True I could have gone the Gundo route, but with a 200 cell cat I thought this might be too noisy. The PSE will allow me to tame it down a bit. I'm currently installing a NHP kit to control the vacuum valves. So far bench testing shows it works okay. Fishing the control wires through the rear firewall is proving slightly painful...
Also ordered - ROW M030 suspension kit from Carnewal. My stock suspension is tired with almost 100k miles under its belt.
More to come...
Last edited by silvergray951; Feb 6, 2017 at 01:34 PM.
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Shiny bits!
. On a similar note, I broke off the oil filler tube but I'll use a 40mm silicone coupler to fix that, again until I remove the engine and can replace the stock one.