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Date Name Message
07/06/2006 10:42:08   cassie   Hi where could I get a sports exhaust from at a reasonable price, and would it imporove the performance considerable?
Thanks
Cass  
07/06/2006 11:17:10   Senor Burt   It will give you a few BHP, noticeable but nothing drastic. It will sound very nice as well. The standard exhaust is very restricted.

Jetex systems are readily available. Check out the links page for their site.  
07/06/2006 12:34:38   Alistair   About 5-6bhp from a Jetex is the rest is standard, but much of that available in the mid range as well as peak power.  
07/06/2006 17:41:43   ian   fitted one last year bought locally....makes a lovely noise and certainly gives more power and much smoother...probably 5-10 bhp....not an easy fit ...  
07/06/2006 17:50:55   Andrew   I got mine from Rolf's Spares (link from here somewhere). It's a Simons (Jetex) and was a bit cheaper than buying from the UK but fitted very easily I believe.  
08/06/2006 14:07:11   Steve H   Year, I got a Jetex (Jetex or simons.com or something like that)after I couldn't get enough of you lot together to get Ken and Mel to make up some more twin pipe systems.

Easy to fit, not too noisy, and good free reving power; but I do miss sounding like a spitfire doing a flypast that you had with the Highgates twin pipe.

Yawn

Oh well - I suppose I must remember im an adult really  
08/06/2006 16:10:58   Senor   You could always get a Jetex front box and have a straight through pipe if you want noise. You could make one in an hour.  
09/06/2006 18:00:45   mark   I put simons universal straight through boxes on mine with a jetex front manifold,got the boxes from my local halfords which saved me the postage!  
09/06/2006 18:31:13   Woody   What is the Internal Diameter of the pipe into the Simons Silencer?  
10/06/2006 09:50:59   Jon   There's absolutely no need to have a twin system, it's more likely to do more bad than good (except for the noise). The exhaust pipe diameter is just as important as the inlet system diameters for fluid flow - too big a diameter and the fluid flows too slower for scavaging (unless you're constantly running at 8000rpm!!), too small and the pipe will restrict flow after a certain rpm.  
12/06/2006 11:40:02   Alex   Scavaging with a Simons header? I don't think so. What I read in the Jack Ashcraft book of V4 tuning is that scavaging is a function of displacement per cylinder and rpm. For the best effect the exhaust gases should merge into one pipe somewhere under the gearbox, preferably a separate pipe per cylinder (as with Chris Moberg's Sonett Yellow Thunder). This merging location should give the best effect at 3500 rpm. The Simons header is way off that situation and the 180 degree turn the gases from cylinders 1 and 3 must make don't do much good either. If you want to improve exhaust performance I think the first thing to do is having a Y-pipe made and mating that with the rest of the Simons exhaust, preferably moving the big silencer to the centre line of the car and a custom S-bend between the big and the aft silencer.  
12/06/2006 12:50:09   Richard   SAH use to do what Alex describes. We made an exhaust using the std headers off the Saab system and welded them to a slightly larger pipe that weht to a Y under the front bulkhead. It was designed for std engines with say a 34 ich or twin choke and it has been stuck on loads of engines and improves performance better than the Jetex.  
12/06/2006 20:45:29   Jon   I've got twin port heads and so made one up from scratch with the Y in the right place under the floor pan. The silencers are located in similar positions to the Jetex system. It's 100% stainless steel too - great sound and make my 120+bhp engine wizz along. But a bit pricey.  
12/06/2006 22:07:37   Alistair   The SAH & Saab S&R systems (Gp 1, not Gp 2 system) both had the Y under the floorpan and were better than Jetex, but these days if you haven't the gear to make one it's a lot easier to buy summat that'll fit.... Or you could always go to your local Powerflow shop & have one custom made out of tissue-paper thickness stainless ;o)

Jetex is OK though, despite that odd bend where the headers join up, it actually flows pretty well (how contorted is the flow out of the heads?!)  
13/06/2006 22:33:20   Alex   No argument about the improvement with a Jetex compared to the original straw that was meant as an exhaust. A friend of mine owns a 96 with a 1700 engine, a Simons exhaust, Weber 32/36 DGV and a Pertronix ignition. It was dynoed at 85 bhp. Not bad at all.  
13/06/2006 23:31:26   Steve H   Yes I do have to say (sorry Ken and Mel) that my 1729 gas flowed head etc.etc. V4 feels better with the jetex than with the twin pipe at higher revs. The twin pipe felt more torque'e at lower revs, but it may have just sounded faster.  
20/06/2006 20:31:01   Jon   Alex,
Your friend's 85bhp car, is that bhp at the wheels or the flywheel?
 
22/06/2006 10:45:47   Kooda   I have just fitted a Jetex to my 96. I'd agree with a 5-6hp gain on a stock system. I got it from Elk parts at a cost of 204 inc VAT which was about 30 cheaper than any other price I could find.

The sound is ok, but my old one was so full of holes it's difficult to compare.

I found fitting it to be reasonibly simple (Ie I didn't have to use a grinder)
Dont worry, I did use the grinder to get the old one off, so my morning was suitibly fulfilling :-)  
22/06/2006 11:10:01   Alex   My guess is it was at the wheels unless some corrective factor was used. I'll check with him.  


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