GregBBRD

I'll actually be able to get pretty close to being able to compare. Two different engines, but pretty close to each other, in terms of design. One had Mark's pipes and the other will have these. Both had very similar exhaust systems. The big difference will be the intake systems. The one that had Mark's headers had a big throttle body and a ported intake. The one we will be testing with these new pipes will have a basically stock intake.

At least there will be some data...

GregBBRD

Stone stock vs. complete exhaust.

No tuning before. Stone stock low mileage perfect GTS. Could have done tuning before...but this tuning/dyno thing can go on forever....or until you go broke.

Thanks. I try very hard at everything I do. I hate things that don't work/don't fit. Glad you like them.

Me, too. I really didn't build these for a stock engine. This exhaust was designed around and built for the big engines. We're really very pleased with the results on the stock GTS engine. This GTS is absolutely a "different" car with these changes. Almost like Porsche made "another" model after the GTS...although the difference between the stock GTS and this GTS is way more significant than the difference between a GT and a GTS!

This thing is really awesome to drive around.

William A

I thought it would be useful, especially for CA 928 owners considering Greg's exhaust system, to pass on that I took my car to get a smog test today. I didn't need it, but I wanted to make sure my car would pass without problems when the time comes.

My brother in law owns a test only smog station. He is the proverbial boy scout, and I doubt he would pass my car if I had the wrong gas cap. I brought the GTS in and asked him to evaluate it visually as well as the full tail pipe test. When he was doing his under car inspection, his comment was that it has headers. My reply was that 928's came from the factory with headers.

Both on visual inspection and tailpipe testing, the GTS passed w/o problem.

When I went to Greg with my goals, I had four in this order:
CA smog compliant, better sound, more power, and a mostly original/non aftermarket look at first glance.

All boxes checked!

slate blue

We are sort of going the way you guys are, sometimes I think stricter. To give you an idea the reason you are not allowed to fit a supercharger is because of the belt noise and whine. My car has to be modified now because bypass are not allowed any more. For cars after 2005 you must retain the same amount of mufflers. You must not cause more noise than standard either.

Headers are not illegal but if they change the characteristics of the engine and that effects the emissions, then they must be removed. Luckily some cars now come with headers, like the M3 and in time this will get confusing.

Greg

GregBBRD

Certainly not "California" legal...almost nothing is. California will pass headers, on a case by case basis...as long as none of the smog components are moved or missing. Obviously, they must firswt pass the testing requirements, which these do. That is the first step towards making these completely legal. The cats are California replacements, not the high flow units that many use. We will now move to step 2, for the California crowd.

BC

Any update on these works of metal art?

Jon B.

I've asked the same thing a couple times and never hear back. Pity, I am in the market for equal length headers for my early 32v, and it's either find some used Devek Lv2's or the ones Mark Anderson used to sell.

BC

I know that Greg is busy with many multiple 928-based hot-irons in the fire. The headers are probably available right now if you were to call him directly at his business.

I was more looking for personal feedback from the players involved, or some more technical info from Greg.

Rob Edwards

I have been remiss in getting back to the dyno to compare vs. my baseline stroker pull with the stock exhaust. It won't be a pure apples-to-apples comparison because of the dy sumped heads thing, but I can put the same ST2 maps back in the brains, as used back in May 2010.

dr bob

Why change the maps back? My rash assumption is that folks improving breathing with headers will improve fuel and ignition maps to take advantage.

Rob Edwards

The headers did make a big difference in the fueling requirements in the upper registers of the map, to the point that I had to up the fuel pressure setting on the FPR a bit. So of course there's going to be a significant power bump with the headers, but how much is header and how much is tuning will be an unknown. I guess I can run both maps on sequential pulls and see how much each contributes.

I can write you a 'script for your rash if you need...

Rob Edwards

I was in the neighborhood today and had Mr. Anderson help me with a quick fly-by in my GTS. Needs to be loud, with headphones. I can do better than this soncially, but it'll give you some idea of the exhaust note. Maybe standing on the bridge over the 57 freeway wasn’t the smartest vantage point from a background noise standpoint….

https://webfiles.uci.edu/redwards/pu...%206-17-11.mp3

Th Dude

Most excellent! That's one smooth and throaty growl.
Btw, I missed you by one day. I made the pilgrimage to Doc Brown's yesterday, to have him look over my new pride and joy.

Mark Anderson

I've had the priviledge over the years to drive some very nice cars but few feel very fast given that my bench mark is my race car with a 5-1 horsepower to weigh ratio. Rob's car hauls ***

cold_beer839

y'all have all the fun.