VIDEO: hear how they sound
Simple test this one; which of the new-style box exhausts for the Vespa T5 work best.
Why?
This is an interesting test because unlike the original exhausts for the PX125 and PX200 engines, which never worked well even before catalysers were added, the T5 exhaust was always surprisingly efficient.
When you bear in mind that this engine is an air-cooled 125 that makes more peak power than a standard PX200 you can understand that Piaggio went to a lot of effort to make the original T5 exhaust work well.
The problem then is that the original T5 exhaust is no longer in production, but the same basic design has been copied and produced as the Sito +, not only for the T5 but the same shape has also been used for other large frame Vespas.
Piaggio clearly got something right at the start!
All of this info has suddenly become more useful again with Pinasco’s decision to remake the Vespa T5 engine casings.
The contenders:
SITO+ (SITO Plus) for Vespa T5
Price: around £85
Available from: SIP
Fit: no problems
Sound: We find the Sito+ louder and more high-pitched than the original Piaggio exhaust.
Construction: This is a replica of the stock exhaust supplied painted matt black. In our experience the build quality is not as good as the Piaggio and they do not last as long without cracking or internal parts rattling around inside.
Comments: The only exhaust still available in the standard layout. Sito + exhausts for the T5 make a decent aftermarket replacement however performance is not quite as good as the original.
Notes: We ran this exhaust on a 114 main jet.
Verdict: a worthy budget contender, but now bettered.
SIP ROAD 2.0 for Vespa T5
SIP ROAD 2.0 for Vespa T5
Price: around £112
Available from: SIP
Fit: no problems however the hole for the main exhaust bolt is very large. As such it needs a big flat washer below the spring washer to ensure a good fit.
Sound: Of the three, the SIP Road 2.0 offered the deepest and bassiest sound which I quite liked.
Construction: This might look like a PX125 exhaust but the expanding segmented cones on the downpipe make all the difference to performance. They are supplied painted black.
Comments: On the dyno the Road 2.0 gave a significant boost to performance compared to the Sito Plus. From 4,000 to 6,500rpm there is a gain of as much as 0.9hp. That might not sound like a lot but it is almost 10% gain in both power and torque. The downside of this is that the SIP Road does not want to rev on like the Sito. From 6,500 rpm it loses power and by 8,000rpm it is more than 2hp down. This translates simply to better acceleration around town, but a lower top speed. SIP are currently in the process of producing homologated versions of their Road exhausts for use in countries where homologation is required. We don’t know how that will affect performance.
Notes: This exhaust needed more fuel and we ran it on a 118 main jet for this test.
Verdict: Makes for a nice punchy ride for carrying a passenger but removes some of the screaming top speed that made the T5 so much fun.
BGM Pro Bigbox for Vespa T5
BGM Pro Bigbox for Vespa T5
Price: around €139 (around £122)
Available from: Scooter Center
Fit: no problems however, like the SIP Road 2.0 the hole for the main exhaust bolt is unnecessarily large. As such it needs a big flat washer below the spring washer to ensure a good fit.
Sound: The sound of the BGM is the racier of the trio and most like an expansion chamber. It is higher pitched than the SIP, but nicer to the ear than the Sito.
Construction: BGM’s exhaust also uses a tapered downpipe to improve performance, but unlike the segmented cones of the SIP, the BGM has a pressed section entering the main exhaust. The name Bigbox derives from the enlarged chamber which will slightly reduce ground clearance over speed humps and kerbs.
Comments: The BGM Bigbox is a good compromise because it produces an excellent mid-rpm gain (up 1.2hp or more than 10% at 5,500rpm) but not losing much to the Sito at higher rpm (only 0.8hp down at 8,000rpm). In terms of overall performance this is a healthy gain to acceleration and drivability at the cost of a little over-rev.
Notes: This exhaust needed more fuel and we ran it on a 118 main jet for this test.
Verdict: A good all-round solution for the T5 engine, boosting mid-range performance whether standard or with a bolt-on kit.
Final summary:
This test proves that peak power quotes never tell the whole story. All 3 of these exhausts make between 11.0 and 11.1hp, and yet two of them produce 10% more torque than the Sito.
In our opinion the SIP Road 2.0 is worth considering. It has a good increase in torque and sounds best, but lack of over-rev will limit your top speed unless you raise the gearing on the engine (one tooth up on the clutch primary gear). It will be interesting to see if they can make a homologated version that keeps the same power characteristics.
The BGM Bigbox, however, is probably a better compromise for use both with a standard engine and a bolt-on kit. If you add a Malossi kit then the torque of this exhaust will help pull a taller (21-tooth) primary gear resulting in better acceleration and a higher top speed.
Sticky
Thanks to Diablo Al, Ellis and Lee for help with this test.
Note: Missing from this test is the SIP Road XL for T5 – a box exhaust designed for higher-revving and engines e.g. Malossi kit for T5. When we re-do this test with a kitted engine we will include it.
In this instance the sito fairs out pretty good! The original was a great design, good revy power/torque balance, nice tone and good ground clearance. Would love to read an interview with some of the original piaggio design team. They did a great job within the space, noise, easy rear wheel removal, spare wheel carrying limitations they had to work with.
hy mates! nice test, but what a pitty that u used the fake t5 exhaust = the bad sito+ as it is completelly empty instead of the good old piaggio t5 exhaust with all the inwards (https://www.youtube.com/watch?v=uMf5ZWVgtP4) the first sito+ also had similiar chambers, then it was – italian like – just removed, looks the same from the outside so what ;o)
all the young box exhausts are based on the as nordspeed (cube) and then pipedesign (pep+ then renamed to pep1 was a original t5 exhaust copy) started to copy them from 2009 on.
so in the end, there is 1 empty box and 2 “full” boxes = this test is only a comparison between bgm and sip road as the sito+ is a really bad exhaust and the worst choice for t5.
could u please add an important information in the text as there are 3 bgm boxes available and u currently dont specify which one it was? its a bbT, the big box touring (BGM1012TR) according to the pictures. the 3 availbale boxes are: bb1 (a complete fail, its more a leovinci, ohne revs and lack of power in low revs) bbS – sport and the third one: bbT – touruing.
greetz
What has happened to the Sip 3 they have been promising us since summer last year?