danglerb

A Y or X if it is properly tuned, length, angles of the merge, diameter etc. give a nice bump to the torque, and changes the exhaust note a bit. If the recipe isn't quite right though it may not do much of anything but sound a little different.

Barry Chan

Thanks for the video, it does sound different, def better than stock, nice rims...

pdejong

The Y-pipe will not do anything for your peformance.
This is what I did on my Us Automatic '83 S.
- MSDS headers barely 10 HP power gain : 218 RWHP
- Y-pipe with Borla exhaust system no difference
- Euro intake system, euro heads, cams and pistons (higher CR) 247 RWHP
- After installing a single 3" exhaust pipe along with a wider Y-pipe I picked up 30 HP for a total of over 275 RWHP

I have the dyno charts to show these improvements.
I can not tell you what this system would have done with the original exhaust headers. Those do not seem to be very well designed, but just the $1,200 MSDS headers was not worth the money.
I made the exhaust myself.
My '90 GT now has a dual 3" exhaust,(along with a twin turbo system) and I have the complete dual 2.25" exhaust system of the GT here. This includes headers. If you're interested in it, I'll sell it to you.

Peter deJong
'83 S (RIP)
'90 GT/TT

Five-8

Peter
If i'm not mistaken, the y pipe i bought from Roger does get to 3 inches (or nearly).And i'm sorry, but i know i picked up some low end torque, might not have been very much, and i don't have dyno charts to prove it...but you'll never convince me that a y pipe to replace the cats didnt change anything.I don't know about the MSDS headers, but i seem to recall lots of folks here happy with them. Perhaps the 5 speeds are able to capitalize on the exhaust freedom somewhat more effectively.

Cheers,

The Fixer

I think the Y was definitely worth the money even though it doesn't unleash gobs of power.
I particularly like that it is much lighter than the cat, the motor should run cooler and the burble and multiple pops when letting off the throttle makes you feel like your in a racing car. We need audio of that.

pdejong

Adrian,
I may not have made this clear: I never had a Y-pipe with my stock headers. I wasn't passing judgement on that.
If you are interested, I'll post the dyno charts. I'll have to scan them. I do not like to go by the seats of my pants. I was trying to get 310 crank HP out of my '83S, just like the '83 Euro had. The MSDS headers resulted in disappointing 10 HP gain. Obviously I had to make a Y-pipe between the header collectors and the stock 2.25 pipe and mufflers. I attribute the 10 HP gain to the headers rather than to the Y-pipe behind them.
What I was saying is, that the combination Y-pipe with stock cat-back system does give you much gain, even with the MSDS headers. The 3" pipe (and muffler) behind my Y-pipe gave me the biggest gain. But I didn't get 310 crank HP untill I had also changed the heads/pistons to Euro parts.

Peter deJong
Charleston SC
'90 GT_TT

Five-8

Peter
Ahh...that clears it up for me, thank you. So your particular view is that the MSDS headers as a stand alone upgrade don't justify the cost.I thought you were saying that there was no improvement in performance by simply replacing the cats with the y pipe to the stock headers, something i "anecdotally" believe to be incorrect.
So Simon (the OP), may wish to get more feedback regarding the MSDS headers, a 10 hp gain is still 10 hp, but clearly the cost is not insignificant.
Hope you weren't offended Peter, that wasn't my intent.

Cheers,

Simon928

Wow, lots of info...thanks for all of the advice! It's looking like a Y pipe with some 85/86 headers would probably be the best bet for me. The cost/benefit ratio for MSDS headers seems to be a little too skewed for my liking.

Benton

Simon, I have a pair of 85-86 manifolds available for $175 + shipping in good used condition. Let me know if you happen to be interested and shipping location and I will get a shipping quote for you.

pdejong

Adrian,

Yes and no offense. I started with MSDS headers AND a Y pipe. HP gain was only 10 HP, which I attributed to the headers. All I was trying to say, if you spend money on a Y-pipe, don;t forget the headers and most of all, untill you open up the exhaust after the Y-pipe (and headers), you don't get the full potential from your Y-pipe and/or headers.

As I said, for anyone interested, I have a complete stock, dual '90 GT exhaust system, including the headers. Be glad to upload pictures.

Peter deJong

'90 GT-TT

Ad0911

I might be interested if you are indeed dutch and live in the Netherlands, as your name sounds dutch.