We've just finished fitting a Fabspeed primary cat bypass on my 1993 3.3 Turbo 2; no pics yet - I'll have to wait until tomorrow now after my digital camera has charged up.

Anyway, a few observations:

1. We only had one snapped bolt; the clamp for the right hand side tail pipe.

2. All nuts came off the exhaust side of the turbo with little effort after heating them cherry red!

3. The lower 3 bolts in the turbo exhaust housing are easy enough to get to with either stubby ratchets or ring spanners. The upper stud and nut was a pain in the ****! Nothing we had would go on and allow us to turn the nut without hitting the cat first. Eventually we sacrificed a ring spanner with an offset neck and cut it down so that it would -just- fit on.

4. You need double jointed wrists to get your hand up behind the back of the cat!

5. The price on virtually all of these cat bypass pipes is too much compared to the size, complexity and quality of the physical product. I've had several aftermarket downpipes/cat-bypass pipes on other cars, which are comparable in terms of size and construction techniques - and they were all cheaper and superior quality. The welding on this one looks as if the TIG has been turned up way too high, with the weld lines actually eating into the edge of the pipe to create a jagged, 'sawtooth' effect. The flange also looks like it is cast - the same as a cheap £90 XSPower/SSAutochrome downpipe I've seen; I'd have much preferred a machined flange on the turbo end.

6. Fit was 'reasonable'. I had to enlarge the mounting hole somewhat and bend the SAI pipe (lucky they have the flexi section in them) to get it to fit, the silencer end flare was also bent slightly, which I had to reprofile with a plastic mallet. No major problems though.

7. I noticed my exhaust tips were looking absolutely horrid, so I took them off and zapped over them with a wire brush and polisher in a drill. My tips were originally black, so I wanted to do them the same colour - unfortunately I realised that we didn't have any black spraypaint left..... not someone to leave a job undone, I grabbed a tin of high temp aluminium and gave each tip 3 or 4 coats. I wasn't sure what it would look like, but I'm pleasantly surprised - it's nothing like chrome, more a 'polished aluminium' look. Nice contrast against the black body.

8. It makes a nice noise
My car is pretty standard, only a K&N filter element in the airbox, standard heat exchangers, standard tips and silencer and now the cat bypass.
The sound is a lot deeper and it barks when you tickle the throttle, rather than just getting louder as revs increase as these cars seem to do as standard. Haven't taken the car out yet, as it's miserable and wet, but it sounds like it should be a lot meaner on the road

 

I've a cat bypass by Scart which is actually excellent workmanship, (but cost around £450) http://www.scart-exhausts.com/ang/de...php?produit=98.
What I like is it actually looks like a cat with its 'muffler' section,... so may fool the MOT tester!

The sound is like you say, but the biggest difference is in the low end torque. It made a big difference. Let us know how yours drives.

 

Some pics as promised...

Bypass pipe fitted...


My repainted exhaust tips...



And also some short movie clips with the new and improved sound of the car ... You'll need DivX or Xvid codecs installed to play these:

Just ticking over smoothly, nice deep bass note...
http://www.fmcc.org.uk/personal_john/911/2.avi

A few revs to hear the difference in tone...
http://www.fmcc.org.uk/personal_john/911/1.avi

 

btw, that standard cat is HEAVY!

 

Just had her out on the road tonight, my what a wonderful noise it makes

It has the most glorious sounding popping & banging above the over-run burble when you give the throttle a blip on a downshift - not quite as harsh as say a TVR, but certainly lovely sounding

To be honest, it's maybe changed the perceived nature of the car more than it has the actual performance - though the mid-range definitely seems stronger now, and I may be mistaken, but the turbo could well be a little faster to spin up. What has changed more than anything is that it now has the aggressive sound to accompany it's perfomance, rather than the muffled drone that these cars seem to have with the standard cat and silencer.
With the windows closed and at 55-65mph however, the noise isn't intrusive at all, very little above normal volume.

 

Sounds like my 930.

 

Sounds like my cat and g-pipe.

 

By the way, is it a dead-cert, if we do both the Cat delete and silencer bypass, we get flames?

 

hi,

i think, it is more a dead cert, that you will get flashing blue lights from behind instead of flames.....

fritz

 

I thought so, Fritz.
But it seems many people do it!

 

it cant be illegal - surely

 

I think you also need short headers/manifolds.

 

I am thinking of getting a bypass pipe to my car.I have already have the G-pip.
No cat and no muffler should get some more HP or what do you think guys?
Hope it doesnt get to load..(sorry for bad english)

 

Welcome to the forum, whereabout in Sweden do you live?
I live 20km north of Stockholm (Täby).

The cat by-pass makes very little difference in sound level, I install my cat before smog inspection every year and there is very little difference I think.

You will get some more hp but more importantly faster spool of your turbo which is a very good thing

 

And if you remove your de-acceleration (over-run) valve you will get large flames at throttle lift