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Discussion Starter #1
I recently picked up a beautiful 88 GT with a N/A 331 and full compliment of Griggs suspension and brakes. The guy I purchased it from had aquired it as is and didn't know much about the build, in fact he didn't know it was anything more than a stock motor with some bolt ons. Fortunately I was able to track down the original builder who filled me in the build. Currently it has BBK shorty headers, off-road x-pipe and two chamber flowmasters with turn downs. I'd like to upgrade to long tubes and a x-pipe with high flow cats. What do you guys recommend?

Stock block
Scat rotating assembly
Ross pistons
Trick flow heads
Typhoon intake
75mm TB
36lb injectors
Unknown cam spec'd by Griggs
 

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Discussion Starter #3
Thanks, it does have a torque arm and a watts link, so it's a little crowded. I'm probably better off leaving it as is, but the motor seems to fall off at about 5600 and I thought a better breathing exhaust may help
 

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Yes, you would absolutely see an improvement with longtubes.

I would question wether the improvements would be worth it or not considering you'd have to spend money on the longtubes and midpipe and catalytic converters. But I must ask, if your current exhaust system is supporting your power levels, why change it?

Then again, if this is a car that was already modified before you got it, your choice of exhaust system might be completely different than the previous owner. If you have your sights set on upgrading to longtubes stick to 1 5/8 primaries for a street/strip car. Too big of a primary will diminish exhaust gas velocity as it exits the combustion chamber.

I have a question about your set-up: you mention its a 331 but also mention stock block, stock rotating assembly... is it possible that the engine you have might be just an overbore to a 306 with pistons in it?
 

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Discussion Starter #8
Thanks for all the replies. I aquired the car as it sits, and like most I'm looking for ways to improve it, but may ultimately leave it alone. The car was built at Griggs racing and I had a chance to speak with Bruce today. It was initially built to be CA smog legal, but that's not a big concern of mine as I'll be registering it in AZ. The car now has a 331 with an unknown cam, but seems more rowdy than the TF stage 2 I had in my last car. Apparently it made 380 to the wheel, which feels fun based on it's 2800lb curb weight.

It's a stock block, but definitely has a scat rotating assembly with a cast crank and forged rods. It has Ross pistons, TF heads, typhoon intake, 75TB, 77MAF, 36lb injectors and the exhaust I mentioned above.

The car will spend most of it's life in my garage, but will get driven hard when it's out. I'd like to maximize the potential of this motor but will likely build something more stout in the future.
 

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Keep it quiet. Flowmasters are OUT.. There's no upside to a loud car on the street IMO...
Depending on the type of Flowmasters you get, it seems those are usually the quieter mufflers. Long tubes and high flow cats should quiet the car down a bit. Honestly do that first just to see what it sounds like.

If you want your engine to not fall off at 5600 rpm just change your intake to a Edelbrock Vic Jr. That intake will move your rpm band upwards, but then again it may be camshaft related too.
 
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