[Jim Doran]

I am contenplating installing a drgas x-crossover for my 65 GTO. My question is I have the 67 HO exhaust manifolds which exit into 2.25 pipe. All the DRGAS components I see are 2.5 and up. Will any adverse sideffects take place if an adapter from 2.25 --> 2.5 -->2.25 for the crossover is installed ? I gotta think someone else been here before.

[Jim Doran]

I am contenplating installing a drgas x-crossover for my 65 GTO. My question is I have the 67 HO exhaust manifolds which exit into 2.25 pipe. All the DRGAS components I see are 2.5 and up. Will any adverse sideffects take place if an adapter from 2.25 --> 2.5 -->2.25 for the crossover is installed ? I gotta think someone else been here before.

[Rocky Rotella]

Jordan, the best thing to do is to either purchase some 2.5" mandrel "J" bends or Torque Tech's mandrel bent lead pipes($109/pr) which are specifically made for those manifolds. To that, run the 2.5" Dr Gas X-pipe and go 2.5" as far back as you can go. Anything past the mufflers isn't as critical as anything ahead of the mufflers.

[Jim Doran]

Ahh, I have the front pipes made for these manifolds, but they are 2.25 as are all the ones in the Pontiac catalogs. I didn't realize someone made 2.5 pipes that mount up to these. Thanks. Any pointers on where to get the Torque tech manifold pipes ? I agree with your point on the mufflers on back not being as critical. I have seen Jim Hand and/or others post similiar data due to the cooling of the gases reducing the volume needed. I was hoping to keep this simple ( read cheap ) and not purchase new mufflers which are already 2.25.

Thanks for the tip, Jim

[Rocky Rotella]

Yup, the exhaust system on my car was fabricated with help from Jim, Tom and Joe Hand. Without their help, I'd have been in trouble. My goes from 3" into 2.5" back by the rear seats.

The Torque Tech lead pipes can be purchased from them directly at 800-408-0016. I have a set in the garage I was going to use on my 76 Trans Am but I had a set of headers custom made for the car by the Hands, so I could'nt turn them down. We're planning on using them on my dad's 72 though

[Michael G]

My first hand opinion.
Don't waste your time and money on the Dr. Gas crossover for your application.
Last year my 4100 lb.(race weight) gto ran 13.3's in the quarter with HO manifolds and a 2.25" muffler shop exhaust.
Over the winter I installed hooker headers into a 3" Dr. gas x over, exiting into a 2 1/2" flowmaster system.
In the spring I took her to the track with 12's on my mind, only to run a best of 13.4.
Then I stepped up a cam size to try and take advantage of the extra exhaust flow.
Still ran 13.3's with a slower 0-60' time.
I have since reinstalled my HO manifolds, exiting into the 2 1/2" torque tech head pipes, then into the same flowmaster tailpipes.
Last week at the track and a dozen runs later
with no other changes, my wife took the fastest run with a 13.32.
Part 2. You "will" also loose the traditional pontiac sound while cruising and gain an annoying exhaust whine.
If there were .3 seconds to gain with the X cross over I certainly didn't see them.
The headers sucked too, but that's another story.

[Jim Doran]

WOW, Michael, your first hand experience certainly seems to contradict what I had expected. I respect your testing and it is going to make me re-think my plan for gaining some bottom end torque. I don't plan to run headers. I am aware of the sound change. Interesting that even when switching back to your original exhaust setup ( but w/new cam ) you stillare at the same level of performance. As I'm sure you know by now, points to something else as the source.

[Michael G]

jrdoran I'm with you on this one. My problem is most likely head flow, or should I say lack of. Which could be the reason the extra exhaust flow didn't do anything for me.
The only thing I wanted to point out in my above statement is that performance gains are not a given when installing the X pipe.
Exhaust systems don't make horsepower, but they can keep it from being made.

[Alex]

I'm also in the middle of redoing the exhaust system on my '68 GTO

I purchashed the ra manifolds from RARE and will probaly go with the Torque Tech 2.5" head pipes

The only problem/question I still have is the flanges to fit the 2.5 headpipes. Dose
anyone make one or do you have to fabricate your own.

Thanks Rocky and Michael for all your help...Alex

[Rocky Rotella]

Torque Tech's headpipes are 2.5". The flange will actually fit either.

[Lee]

MichaelG,

Did you re-jet your carb, after you changed the exhaust? Those changes should have leaned out your mixture, requiring richer jetting. Just like running open headers, the car won't run any faster unless the carb was way rich to begin with, or you richen it up.

Lee

[Michael G]

Lee, I even went one step further.
Switched from a 750 Eldelbrock to a 750 speed Demon. Purchased the holley jet kit and moved up 4 sizes to #80's on the primaries and 2 sizes to #85 on the secondaries.(tried 87's)
Installed a Carter electric pump to help maintain fuel pressure. Also had the distributer recurved, running 33/34 deg total all in by 3300rpm.
The last thing I was going to try "before" I gave up was an Msd 6AL ignition box and converting to a 1/2" fuel line.
If all goes well, a much lighter 67 bird will hit the track next year and the GTO will retire to cruise nights.