Well....I Installed my new Nameless downpipes this afternoon and it went fairly smooth. If anyone else decides to tackle this job I would re-iterate the shortening of the studs as was suggested to me by one of our wonderful members here on the forum. The length creates a big hassle in that you need to use a deep well socket in order to get down to the nut in an area where there is no room for it to stand up straight and "seat" on the nut. At least 4 of the 8 studs are nearly impossible to reach, so i just cut those which i knew I would have trouble with. I'll find his name later so he gets the cudos for that suggestion.

Another thing is that the connectors for the O2 sensors were also hard to get to. The rt. side was a task, but the left side I found easier to access with the lower windshield shroud removed (I think thats what you call it/ the plastic that funnels down to direct the rain water back from the engine). JTIS shows that both sets are on the side of a module above the Tranny, but that is not so. A pair is attatched to the back closer to/ against the firewall.

Looking forward to installing the Mina exhaust on this weekend so I can post up a video/sound clip for you guys.

Peace,
Bruce

 

It was Daddyo007 who gave me the tip of cutting down the studs on my new Downpipes. Thanks Daddy! (feels weird saying that)

Thanks Daddy!,
Bruce

 

What sort of gains do you expect from your mods?

 

By gains I would hope these are actual measured one rather than subjective "feels more powerful" ones.

Doug

 

What, you don't have faith in the butt dyno?

 

I believe that Jason at Nameless has those dyno tests but I think you have to realize that many people who replace the cats will also replace the rest of the exhaust system because of the restrictions back to the tips. If you saw my video of the exhaust i pulled out of my car you can see the tight bends over the axle cutting the air flow in half not to mention the mufflers/resonators. I went with the Mina mid resonator delete/ under the differential set-up as suggested by Dan Russo here on the Forum and owner of AJ Motorworks LLC

 

When I had my Corvette there were all sorts of add-on goodies I did with each one claiming horsepower increases of anywhere between 5 hp to 30 hp, depending on the item. Naturally my butt dino (and ego) convinced me that I was getting some actual benefit by doing these addons but if you believed all the advertising you could get up to 100hp by adding up the claims of the various bolt-ons--obviously not true.

The ONLY add-on I did where I could honestly feel a difference was when I went into the engine and upgraded the rocker arms and valve springs. Dyno results from others with similar cars confirmed that that mod was honestly worth at least 25hp.

On the other hand by far the most popular "performance" mod most owners did right away was the exhaust system. However, those who did before and after measurements never found an increase of any more than about 5hp for this relatively expensive mod. On the other hand there was a change in the exhaust sound but just as many folks complained about droning that they now had inside the cabin versus being happy with the louder tone.

I have been trying for a while now to get a definitive straight answer as to what measured results you get on an otherwise stock XKR by dumping close to $1,000 into downpipes and if the resulting increase in noise would be objectionable inside the car.

Doug

 

I am in the process of adding these downpipes. If I get another couple of horses thats nice, but I am really just doing this for improved sound. In another month I will be able to give my subjective opinion on whether the resulting noise becomes objectionable with only the downpipes changed. I'm keeping the old Cats in case I want to put things back. I admit, its an expensive experiment but I haven't grown up yet - that's my excuse.

Stuart

 

i am another like stuart,68 1/2 and still feel young when im in my car

 

I suspect I will eventually get around to looking more seriously into the downpipes since it is just one of those "man things" to tinker around with something mechanical. But the pricing of these and the cost of installing is just beyond what I care to spend right now for something that will really not give me much more than sound. However, knowing that the sound is pleasant rather than objectionable (particularly inside the cabin) will help sway me to keep considering and possibly purchase the next time there is some special promotion of sale.

Doug

 

I guess you're not familiar with the stock cats. At the very least you're losing 25-30 lbs dead weight by switching to high flow cats. Not to mention, you're going from a horrible design with a 90 degree bend to one that is much more efficient, however if you'll probably want to replace the stock over the axle pipe to get the most benefit from the new cats.

The stock Jaguar exhaust from exhaust manifold to tailpipe was not designed for performance at all, it was designed for noise reduction. If anything, the design actually robs a bit of performance. Unfortunately, fixing Jaguar's horrible design isn't cheap, but it's not a cosmetic one.

I do plan on dynoing my XKR soon, so I'll be able to provide some numbers that can be compared to stock numbers...

 

Quote from Xenophobe (I cant figure out how to properly quote someones post) "I guess you're not familiar with the stock cats. At the very least you're losing 25-30 lbs dead weight by switching to high flow cats. Not to mention, you're going from a horrible design with a 90 degree bend to one that is much more efficient, however if you'll probably want to replace the stock over the axle pipe to get the most benefit from the new cats."

Same goes for the center muffler which I replaced. Bought from XKs unlimited. Here's what they have to say about it.............

"High Performance Exhaust Systems. There's really only one problem with the exhaust note of the first-generation XK8: It basically doesn't have one. We offer several options to correct this deficiency. All of our exhaust systems are made in England from type 304 stainless steel. All pipes are bright polished. Mufflers are bright annealed. Option Three. The final piece to the exhaust puzzle is a high-performance stainless steel front muffler. These are less restrictive straight-through designs and are about 20 percent lighter than original pieces."

http://partsxks.com/i-7088588-17-036...n-s-c-xk8.html

 

LMAO ccfulton. Classic

 

Nearly 18 lbs, to be more precise. And that's with non-cat downpipes. High flow cats would save less weight.

 

Just press the "quote" button on the bottom right of someone's message.


You'll get far more weight savings by changing the cats. Mufflers aren't all that heavy. The center muffler weighs less than one stock cat. I replaced my OEM center with a Borla dual in dual out with the internal crossover. I don't know how much weight (if any) that I saved but it couldn't have been significant.


Ah, I haven't actually weighed them. I'm fairly certain both of my NP cats weigh less than one OEM cat. I don't know how much they weigh, but they're surprisingly heavy castings.

 

Yes--all (potentially) meaningful improvements if you want to shave that hundreth of a second off a quarter mile time. There are all sorts of restrictions in any passenger car system that might make a difference in quarter miles slips but not so much in daily driving. I recall guys at the Corvette forum complaining about how the stock throttle body was restrictive so they would install a larger one, then typically finding performance either not improved or actually worsened. Two things--the stock throttle body would only be considered restrictive if the engine was operating under the greatest rpm conditions without other restrictions and the swap was only beneficial if everything in the system was addressed as well. The entire system is really only a large air pump so improvements need to be carried out throughout the system (intake, heads, valves, exhaust) to derive benefits.

So while the over axle exhaust system in our cars is obviously a bonehead design compared with straight through, what do you get in terms of bang-for-the-buck in the normal day to day driving that I suspect 99% of us here do?

Doug

 

For half the money it takes to mod an exhaust system for 5-8 HP, one can do a larger lower pulley mod on a 4.0 XJR and gain 50hp in mid range. That's something easily felt in daily driving-we all do passing on a freeway or open road. The rest of the money I'd probably spend on LSD.

I'm not bagging on the exhaust mod - aggressive sound is good. In terms of weight saving on a 2 ton car I doubt it will make much impact. I guess I'll just leave it to individually perceived priorities.

 

It's probably time you trade your Jag in for a Prius or Volt.

The reason I upgraded my cats, center muffler and added a Mina exhaust is because I'm upgrading my supercharger to a twin screw. The OEM cats and exhaust aren't performance oriented at all.

I'm not driving a jag because I'm a snooty old fart trying to look pretentious while they optimize their gas mileage. lol

 

So that's the well-thought out conclusion you reached by my questioning the benefit of exhaust mods?? If you are doing all sorts of other things that logically lead to improving the exhaust system, that is another story. But those folks that jump right into doing an exhaust mod by itself because it is a relatively simple bolt-off-bolt-on operation who think they are going to get anything much more than some sound might be disappointed. Clearly I have always been talking about bang-for-the-buck.

Doug

 

Agree w/ Seismic Guy that downpipes are a lot of money for not much return in HP. The benefit of a throatier tone might make it a more attractive, but still a lot of money. And the ads we see for some bolt on HP gains from some mfr, like air filters, and mufflers are ridiculous. Not referring to Nameless here... just in general.

Having said that, if you are boosting and are beginning to move serious amounts of airflow, then yes, every restriction and bend is robbing your power output. So yes, dumping the right angle turn, and adding downpipes with a smoother flowing pipe system makes good sense. Just changing to dual intakes, split DPs, Test Pipes and a bigger diameter free flow exhaust, with no other changes, are good for an extra 50 HP on my 300zx Twin Turbo.