Blueman33

What would be an educated guess for the performance difference on a lightly modified 951 of

1. bursch test pipe vs.

2. exhaust OPEN right after the WG tie in?

Thanks in advance.

In case you're wondering, I am toying wtih the idea of putting a valve that can be open and closed to exhuast to atmosphere directly after WG tie in.

Mike Buck

#1 - maybe a slight decrease in spool time. if your stock cat isn't 100%, it will be more apparent

#2 - a .000001 increase in hp and 100 dB increase

Peckster

Most loud bike exhausts make LESS hp than stock.

Sam Lin

Peckster, I'm not sure which you're referring to. On the Hayabusa, aftermarket pipes are worth a solid 2-3 hp after the computer is remapped for them.

Sam

Blueman33

Mike,

There is no cat. I have a cat bypass pipe.

I am wondering if putting in a valve to make it a straight pipe on demand is worth it.

Matt H

The canister on a bike is good for nothing, the entire system with rejetted carbs is good for quite a bit. 2-3HP on a 'busa is like adding 1 HP to your 951, nice to say you did but not worth much in the end. Sam - do you have a GSX1300R? They are rocket sleds in a straight line, but I didnt like the feel of it around town.
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Sam Lin

Matt, my dad's got one of them, he really loves it - btw, no more rejetting carbs on the newer bikes, it's been full fuel injection for years. Ours is stock, as you said, 3hp is really nothing and my dad doesn't want it any quicker.

Blueman33, try looking at an electric exhaust cutout, that's the most convenient way to run a cutout, my friend has a pair on his Lightning for the drags. As for the difference, you'll spool quicker with the cutout, so gain some torque under the curve, but overall hp should be the same.

Sam

User 41221

Boy, I really have to disagree with your comment about loud pipes, at least as far as Harleys go. Swapping from the stock pipes to a set of Kirkers on my FLHTC made a good sized difference, documented on a dyno, to the 5hp peak, and GOBS of useable torque. Granted, on some of your "superbikes", the factory exhaust is already pretty well tuned.

To answer your original question, blueeman, the key is the phrase "lightly modified". It won't make any difference, performance wise, for you car. If you want to get LOTS of scutiny by the local gendarmes, its definitely the "ticket"! lol

Regards,

Blueman33

Scott,

I'd turn the thing OFF for the cop and say, "what? that noise was a Harley, you didn't see that thing go by? that wasn't MEEE"

You see, with the flip of a switch the valve opens and closes..........or even opens half way. I would open it for track.............and maybe once in a while on the street just to be a nut.

But it seems like a waste of money if it's just going to m ake the car sound obnoxious

RAPID944

Stock PORSCHE 951 S, '90 with free flow 3'' exhaust.

233RWHP 238RWTQ