As some of you know my WRX Wagon appears to have what looks like the channel tunnel masqurading as an exhaust (see first pic

Too big a bore on an exhaust can harm the torque, as long as the bore itself is between 2.5 and 3 inches (I believe) it should be fine. BTW Bore does not mean the outlet on the back http://bbs.scoobynet.co.uk/smile.gif but the size of the pipe before the back box itself.

The way I understood it (I may be wrong, so I've got me coat ready), is that reduced back-pressure <I>reduces</I> the time required too spool-up the turbo. I thought it was because the exhaust gases are travelling faster (less resistance), and so gets the turbo up to speed faster. Is this right.

Keith (Coat in hand)

Ian:
Any idea what size bore an HKS SuperDrager has????

Not 100% sure Markus but i think its 3 inch ? although there are a number of HKS owners on here that can put me right if i am wrong.

I have an HKS super drager and I think the actual pipe size is a 3inch bore with a four inch tailpipe. Less back pressure means the turbo will have less resistance when it's spinning, back pressure can be restrictive but you need some back pressure on a turbo car if you want better response, less lag. This is one of the reasons why those 1000bhp skylines etc.. have bugger all low down in the rev range and then scream off once the turbo is spinning. Anyone else care to elaborate? The HKS is a good system though, my car is a UK98 and produces 286bhp with the HKS exhaust, filter, and boost controller!

NITO:
What's your low rev range performance like then?

Pretty happy that the car is coming with this type of exhaust, though it's a bit bigger than I might have fitted, but one should not grumble.

It's not too bad at all Markus. Mines a '98 uk car so they have less lag anyway due to the smaller turbo. I suppose the car starts to pick up nicely from 2500-3000rpm and then at its best from 3250-5000, it makes max torque at 4000rpm but revs happily all the way to the redline. I'm happy with the exhaust choice. I would be too if I were you..I know what you mean about it being a bit large but just think..you didn't have to pay out the £680 to buy it. What is also nice is the fact that the pipework is aluminised mild steel instead of stainless which means you don't get a horrendous booming/droning in the car on motorway trips. It'll sound nice until it eventually rusts!!lol!

The exhaust could also be the HKS "Hiper" which is a 3" straight system (minimal bends and twists). I have that now fitted to my Wagon STi 2 with a Scoobysport downpipe at the front end and IMHO its one of the best combinations. Very strong mid and top with no appreciable difference in low end. I suspect the SS downpipe, being "necked" to 2.5 inch for the standard system, helps the turbo (mine is a TDO5H sleeve bearing item which is much laggier than a ballrace unit)

By fitting the HKS I gained 19 lbft more peak torque and 12 bhp more peak power.

Fitting the SS downpipe shifted peak torque 600 rpm lower, fitting the HKS afterwards did not move it from that point.

Bob

hmm, rusts! did not think about that! As the car is an import I've no sure way of telling how long it's been on the car.

<B>Pretty happy that the car is coming with this type of exhaust, though it's a bit bigger than I might have fitted, but one should not grumble.</B>

Your kidding, right? http://bbs.scoobynet.co.uk/smile.gif Grumble is all it will do http://bbs.scoobynet.co.uk/smile.gif


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Fullonloon:
cool!

My only concern is that the cat might decide that the nice warm pipe would be an ideal place to sleep!! guess I'd get more than a grumble then if I started the old girl up!

I've just checked and can confirm that the Super Drager is a 3" pipe with a 4 1/2" (115mm) tailpipe. I had the Hiper muffler briefly Bob and agree that for performance it was excellent (I have the HKS downpipe). As mine is my everyday road car I had to remove it simply for the noise it made. Suprisingly at high revs it wasn't that intrusive but at low revs driving through town it just sounded way too much. I would have been nicked in no time. I loved all the spluttering and burbling, and it never caught on the road either which was nice. In all I prefer the Drager for everyday use but as your Sti2 is I imagine, your track car then it's perfect! When the Hiper was fitted to my car and road tested by the dealer, the dealer principle rushed outside as he thought the mechanics were messing around with their rally car!!

sorry for diversing the topic a little,but has anyone got any thoughts on the various s/steel back boxes on the market,would like a magnex, but might look a little too "max p"

any suggestions would be welcome

regards

I think the Magnex is one of the least Maxy P. If you do want the Magnex and don't fancy the oval tailpipe, if you buy it from Roadrunner in Nottingham you can get it with a 3.5" round instead of the oval. This is exclusive to them and looks better than the oval IMHO!!

thanks nito,ill try them,didnt realise there was a round pipe
ta

ROADRUNNER IN NOTTM ALSO do a MAGNEX 4" round end pipe as well, I got one from them, sounds a whole lot better than the standard impreza twin pipe!!!!! cost £218.50, cat pipe is £98.50, full system around £300.

[This message has been edited by salsa-king (edited 18-03-2000).]

Markus, are you sure that is an HKS muffler? Judging from the sticker on your bumper I would say it is an Apex-i N1 muffler. These are designed to have the minuimum amount of bends possible, often not following the manufacturers original routing.If you look at the backbox from underneath, maybe you will see the manufacturers name engraved or stamped on it. Look under your car to see if it has cats or not.

It does look more like the hyper or the N1 than the superdragger but i could be wrong. The superdragger has a larger backbox camber and from your pics it looks like its pretty straight.

I used to have a Apexi GT exhaust (http://202.72.16.198/backright.jpg) which was very thick all the way, incredibly boomy and suffered from a non responsive low end ( 2-3000 revs). Bloody great top end though, finally got fed up with the noise and fitted a more descreet exhaust. Could tell the difference straight away, a LOT more responsive. (http://202.72.16.198/outside3.html)

I think my first one was a bit over the top..