[Ron Sutton]

Ok, the exhaust is critical. Can't stress that enough.

If they can find, or afford to have built, a 4-2-1 header set-up, that would be optimum. I'd be happy to map a system out for you. But I suspect not, so I've outlined a 4-1 exhaust system.

The headers need to be "Step headers" starting with a 1-5/8" primaries out of the head & stepping up to 1-3/4". 34"-36" long primary tubes.

FYI: All the dimensions after the primary header tubes ... are measured from the end of the primary tubes up inside the collector.

The collector needs to be 3" in diameter ... with a true "merge collector" diameter of 2-1/2" installed at 9.9"± from the end of the primary tubes. People often confuse collectors with merge collectors because the names are similar. A true merge collector necks down at a specific point & then necks back up. See the attached photos.

If the merge collector is designed correctly ...
* The 4 tubes come into the necked down area of the collector at a 10° to 15° angle
* There is a "merge tip" at the end of the primary header tubes, in the middle of the 4 tubes, that comes to a point.
* The collector necks down & then necks back up, forming a venturi.

I like, use & recommend Dynatech merge collectors & headers. They have the best "affordable" merge collectors. There are places that build merge collectors costing insane money that work about the same as the lesser expensive Dynatech versions. Warning: There are a lot of inferior designs that cost the same & even more.

For this application, the centerline of that venturi neck down needs to be at 9.9"± from the end of the primary header tubes.

The front edge of the opening of the H-pipe needs to be at 19.8"± from the end of the primary tubes. This one is very sensitive. Don't vary more than a half inch at most. Less is better.

The X-pipe (photo at bottom right) needs to be centered at 39.6"± from the end of the primary tubes. This one is less sensitive ... and inch or two either direction is ok.

The mufflers need to be centered at 79.2"± from the end of the primary tubes if possible. This is getting close to the suspension. If this won't work, they may need to eliminate the X-pipe & place the mufflers at 39.6"±. Unless they're running a "straight through" type of muffler, then placement is a non-issue.

If you need to vary from these dimensions, don't vary much, as you are upsetting the exhaust pulse timing. If you need to vary a lot ... let's talk first. It is better to have no H-pipe or X-pipe ... then to have them in the opposite location from optimum.