Merry Christmas Guys, I had to upgrade my 348 even though I just bought it. Kind of need to make it my own. Just bought the drilled dead pedal and pedals. rear wheel spacers to give it a wide stance, Chrome parancing horses for front and back as mine are black for some reason? I need to take through DEQ then the Cats come off and test pipes. Does anone have some advise on removing the CATS and putting on the test pipes? Will it pass DEQ without the CATS? Is it even smart to remove the CATS. It just sounds to tame the way it is. I wil be buying exhaust later so any advise on which exhaust system to by for my 91 348 would be appreciated. Tubi, Ansa ect? Happy Holidays!!! Mike
I have a Tubi - and Hyperflow Cats that I like on my 355. But I don't think the Hyperflow cats (Flow within 4% of straight pipes- and have small internal volume) make it sound any better than with the production cats. The reason I think is that the larger physical internal volume of the production cats forms a resonator effect which enhances the Tubi. This enhancement cancels out the muffling effect of the production cat producing no net difference in noise level but a slight shift in tone. When I had my car apart recently I was really tempted to loose the Tubi and just have a muffler shop make me a couple of 2 ft straight pipes just to see what it sounded like, but I chickened out. The one thing the tubi does is deepen the exhaust note by creating a resonance that seems to coalesce the high frequency pulses to drop the tone by at least one octave. I'm guessing it would have been significantly louder with the straight pipes but I don't know whether it would have been a deeper tone.
Thanks for the imput.I heard tat the cats cause problems with the check engine light coming on and by removing them and going with straight test pipe and leaving the stock muffler you improve not only the sound and slight HP increase but lessen the check engine light problems???? Tset pipes are only $339 and take the place of the cats.I don't know any feedback would be great?
Mike, A. Run the test pipes. That way you won't have to worry about burning up your cats for one reason or another (thats what the "check engine" lights are for). The cats can always be reinstalled later as required, or not. B. While you're at it, put a Tubi on there. It too can be removed and replaced as required. C. All or none! Go for it! Don't look back. Enjoy the music.............................. DJ
The "check engine" light isn't triggered by the cats - that's the "slow down" light. And that particular problem is usually caused by faulty cat temp ECU's, not by the cats themselves or their thermocouples.
My mistake. I have the same "slow down" lights on mine for the same reason. Just misread what Mike wrote.
I wil get the Tubi..Need the dust to settle first. Before summer I will have the Tubi but gonna go with the test pipes to get those cats off. As long as you see no downside to doing so.
Only potential downside is smelly exhaust - my 348 spider had punched cats when I got it and I smelled like fuel after a run. Went with Hyperflow cats and am really happy with them - passes Cali smog check with flying colors and sounds great with the Tubi/Hyperflow combination. Not as cheap as your test pipe deal though, but I can pass up all of the "no cat" threads and sleep well at night. Cheers Kevin
Excellant Point Kevin...With a new clutch and some other issues with my new ride the test pipes might be the way but will most definatley updrade to the Hyperflow cats eventually
See how you go - with the spider I hated the stink, you may be better off with the ts. Also just looked up the thread a bit and I'd be surprised if you could pass DEQ without cats. Here is my "punched cats, stock muffler" emissions test numbers, which I should think might be similar to your car with test pipes. You can check your DEQ requirements and see how close you would be to passing based on these. Cheers Kevin Image Unavailable, Please Login
