Exhaust

The exhaust system on my 91GT is all rusted out and basically falling apart. I need to get it emmission tested and need to buy some new parts. I just have some questions to ask first.

1) I will be retaining stock headers for now as i will be upgrading to twisted wedge heads soon and since the headers that fit stock heads dont fit twisted wedge heads, i figure it will be a waste of money. Are my stock headers considered long tube?

2) Would you recomend the MAC 2.5" prochamber over other X/H assemblies?

The stock headers are not long tube, they are shorty's.

thank you, and are the collectors on those headers also 2.25" like the rest of the exhaust?

It's a ball and socket connection. They will fit either the stock 2.25" mid-pipe or an aftermaket 2.5" mid-pipe. This is because either one will have a flare designed to fit header design.

will there be any problems w/ me intalling long tube headers on my 91GT?

The Twisted Wedge heads use the same headers as your existing stock heads. The Trick Flow high ports are different (and are not reccomended for a mild application).

The MAC ProChamber is a nice choice and the design makes power over an H-pipe. However, I'm not sure it's worth much over the X-pipe design. Since you mentioned emissions I'd have to recommend an X-pipe with cats such as those offered by BBK. MAC does not make a catted ProChamber.

Longtubes will make more power as well, but are not emission legal either. However, with cats they should not hurt emissions enough to fail...as long as you can pass the visual with them (most inspectors only look for the cats). The major drawback to the longtubes is ground clearance as they do hang down considerably lower.

My car currently wears Twisted Wedge heads, MAC 1-5/8" equal-length shorties, a 2-1/2" ProChamber with welded in cats, and passes the "sniffer" test with ease. It did not pass until a I welded in the cats however, and they only cost me 5 lb.ft. of torque...suprisingly no HP loss. The car is very low and the ProChamber/cat setup does not clear speed bumps well. In my case longtubes are currently out of the question, and if I had to do it again, I'd probably have used a catted X-pipe (for a little extra ground clearance).

Good luck.

ok, i always thought the twisted wedge heads used different headers than that of the stock heads. So, since im doin my exhaust now, i suppose i will get them. How much did you lower your car? I eventually plan on getting some lowering springs and possibly new shocks, struts, and control arms. The loweringsprings will lower the car 1"-2". I will be getting shorty headers as they are less expensive anyways. If your prochamber hits on some bumps, then also doesnt your mufflers hit?

well, for my setup up i plan on getting 1 5/8" equal length shorty headers, BBK X-pipe w/ converters, and 40 series 2 chamber mufflers.

Trick Flow Specialties' Twisted Wedge heads use the standard exhaust port configuration. Their older/rereleased High Port heads have the relocated exhaust ports.

My car has a Maximum Motorsports suspension with H&R springs, and sits approximately 1.5" lower. 2" is too low for these cars...the alignment geometry is greatly affected. If I had my way or were to do it all over again, I would install coil-overs up front and rear lower control-arms with adjustable spring perches. With this setup the ride height is fully adjustable and I would probably only lower th car approximately 1". You can also jack up the rear to clear slicks better when at the strip.

*note: if you change the springs, you should also change the shocks & struts to match the new spring rates you have chosen.

The mufflers rarely touch, due to their location. The Prochamber and cats are a different story. I have to go over speed bumps at an angle...like a low-rider[img]/phpBB/images/smiles/icon_rolleyes.gif[/img]

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On 2004-01-12 17:00, scorcher2005 wrote:


well, for my setup up i plan on getting 1 5/8" equal length shorty headers
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Hope you got small hands and alot of bandaids.

so would you even recommend equal lengths? Because i recently read another topic about it and was wondering the same thing, with all those bends how is there any performance gain at all?