Downpipe / Midpipe replacement

Commercially available exhaust systems are few and far between. It's not that they don't exist, it's just that most vendors don't even know what is available for the All Trac/GT-Four. We have listed for you part numbers, and some thoughts that might help you decide which is best for you. A separate ST165 version of this page will be made later.

If you have questions about making your own exhaust system, visit here: EXHAUST FAQ

Brand Pipe Size Material Coating Braced? Cost Notes
Greddy 3" Steel Aluminized No $199 Does not replace turbo elbow
Blitz 3" Cast Iron Thermal OE Braces $395 Does not replace turbo elbow
Top End 2.75"-3" Steel Hi Temp Paint 1 Brace $325 Screw in style o2 sensor
Trueleo 3" Steel Baked Coat No $250 Painted version, $225, OE style o2
KORacing 2.5" Steel Ceramic No $295 OE style o2, optional 2nd o2
Aussie 3" 3" Steel HPC option No $300 2nd o2, comes with ALL gaskets

KORacing Downpipe


PRO: 2.5" fits better with stock midpipe and good for street

CON: Price went up

Custom MR2 downpipe (not yet tested with st185)

2.5" mandrel bent (3 piece)

Mild steel construction

Laser cut flanges

Uses OEM style o2 sensor mount

$275 w/ ceramic coating (OEM o2 sensor style)

$15 extra for extra o2 bung

$20 shipping

KORdownpipe1.jpg (77207 bytes) KORdownpipe3.jpg (73382 bytes) KORdownpipe4.jpg (62815 bytes) KORdownpipe2.jpg (109985 bytes)

Aussie Downpipe


PRO: Amazing pipe size and smooth looks, 3" nice fit, higher flow gaskets included

CON: Blocks oil filter (st165)

3.5-3" mandrel bent (3 piece)

Mild steel construction

Uses OEM style o2 sensor mount as well as secondary o2 port for tuning

$325 shipped with HPC coating

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ST165 DP ST185 DP


Custom st185 downpipe

2.75" to 3" mandrel bent

Mild steel construction

Includes new o2 sensor (requires custom wiring)

$325 ($400 after modification)

PRO: Always in stock if you need something ASAP, includes new o2 sensor and cheaper style o2 flange

CON: Boost spikes on some cars

*Note some have complained of boost spikes due to the lack of space around the wastegate area. To solve this problem you may have to modify the pipe to allow the wastegate door to swing completely open. Here are some pictures of a Top End downpipe that has been modified to work correctly.

Trueleo Downpipe

No Longer Sold, information will remain for reference

PRO: Inexpensive, higher flowing 3" for maximum HP

CON: Not braced, flange not laser cut

Custom ST185 downpipe

3" mandrel bent (2 piece)

Mild steel construction

Uses OEM style o2 sensor mount

$250 w/ ceramic style baked paint

$225 w/ hi temp paint spray

$??? shipping

TrueleoDownpipe1.jpg (34110 bytes) TrueleoDownpipe2.jpg (30078 bytes) TrueleoDownpipe3.jpg (51556 bytes) TrueleoDownpipeInstalled.jpg (275720 bytes)

Offroad pipe (diffuser), primary cat replacement

PRO: Cast iron for extreme durability, full 75mm outlet, smooth internals for maximum flow.
CON: Expensive, only replaces catalytic converter.

$395 Retail, Fits ST165, ST185, ST205 PN#

Trust 75mm Downpipe (cat replacement)

PRO: Less expensive than Blitz unit, Full 75mm outlet.
CON: Special order only, 3" outlet mated with stock midpipe will cause turbulence.

HKS Offroad downpipe

This unit is no longer made or sold. The picture here is basically a reference and shows how simple it can be to make a cat replacement pipe. Assuming making a copy cat top flange was about $35, the entire unit could be done for $150 or less.

Do it yourself??

ST165: ST165downpipe.jpg (61153 bytes) ST185: ST185downpipe.jpg (405991 bytes)

Here are a couple of custom down pipes that were made as a one time only type of product. Anyone with enough time and patience can do this. As you can see you basically need the flange that goes to the turbo, and the appropriate piping *preferably stainless steel*. As you can see by these pipes, several small sections had to be welded together to make the shape and fit correct. Ask either one of these two people and they just might say they would never do it again!

Want to make a downpipe? Here are your turbo flanges! The 4 bolt is ST165, the 6 bolt is ST185/MR2. They are available for $35 each. Email Us.

ST165flange.jpg (40448 bytes) ST185flange.jpg (41472 bytes)

A custom downpipe made at home. This one is also from Australia. Boy they really know how to do it down under! (ST185/MR2)

ST185dp1.jpg (393856 bytes)ST185dp2.jpg (431047 bytes)ST185dp4.jpg (350849 bytes)


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