One Piece Valve
Our valves are not finished from generic blanks rather they are specifically designed for each and every application. We work relentlessly, testing and researching every aspect trying to improve the air flow of our designs.
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Ships within 48 hours · Estimated delivery Aug 17 - Aug 22
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Description
Supertech Inconel Exhaust Valve Set of 12 - BMW N54Production of our racing valves begins with a one piece forging, where the head of the valve is forged under a slow two step process to keep a good material grain flow. The forging is then CNC machined in several steps to ensure the precision of the final dimensions. We then do another heat treatment for stress relieving followed by a nitride hardening treatment (or coating process depending on the application). Lastly, we do one more grinding,
Production of our racing valves begins with a one piece forging, where the head of the valve is forged under a slow two step process to keep a good material grain flow. The forging is then CNC machined in several steps to ensure the precision of the final dimensions. We then do another heat treatment for stress relieving followed by a nitride hardening treatment (or coating process depending on the application). Lastly, we do one more grinding, followed by our patented Superfinishing of the surface to ensure that each valve is free of any imperfections and the dimensions are precise.We apply more than 30 years of experience in the development of each and every Supertech racing valve we sell. Combine this experience with state of the art equipment such as ultrasonic tests, x-rays, laser measurement equipment, and applications like computerized Finite Element Analysis (FEA) and it is no wonder why supertech has some of the best performance products on the market.
While this is more than most manufacturers we dont stop there. We also do extensive testing working very closely with many of today's top engine builders in order to continuously improve our products. All of this is meant to insure Supertech's industry leading reputation for high flow rates, durability and uncompromising quality.
Durability
With every valve design we strive to maximize durability through higher fatigue resistance and tensile strength. Each valve tip is hardened beyond 52HRc.
Strict Tolerances
Its unlikely you will find any of our competitors valves with stricter dimensional tolerances than our Supertech valves. Combine that with finished seats with equally strict run out tolerances and you wont find a better sealing, better performing and easier to install solution anywhere!
Higher Flow Rates
Optimum high flow rates are achieved by ensuring that our valves are manufactured with the best angles for each application. We consider back cut, under cut and valve head angles for each application to produce the optimum high flow rates for each application.
Superfinish
In 2006 we introduced our stem Superfinishing as a standard addition to all of our valves at no additional cost. When our Superfinish is combined with our Black Nitrided valve, it reduces the surface roughness to 1/3 of our chrome coated valve. The end result& unsurpassed performance and durability.
- Head Diam: 28mm (std)
- Material: Inconel-Nimonic / Sodium Filled
- Groove Type: Single Groove
- Length: 112.9mm
- Stem Diam: 5.96mm
Replaces OE Part # 11-34-7-573-840 / 11 34 7 573 840 / 11347573840
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.1 ★★★★★
Based on 24 reviews
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Product Reviews
★★★★★ 5
Great product!
Style: 30 sqft
I can say this product makes a huge difference with road noise and is cleaner and easy to work with when applying compared to other mats that cost about the same price.
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Reviewed in the United States on February 14, 2026
★★★★★ 5
Very heavy and thick
Style: 30 sqft
I purchased mini brands of sound ending and this is by far the heaviest sound deadening I've ever ordered. I'm not installed yet but I have a good feeling that is going to work exceptionally in blocking sound. If weight is a concern for you I would recommend a lighter product however if sound quality and a quiet ride is your priority this is the one for you.
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Reviewed in the United States on March 18, 2026
★★★★★ 5
Siless Hybrid 3-in-1 - Far Exceeded my Expectations!!!
Model: SLH20025
I recently installed the Siless Hybrid 3-in-1 sound deadening mat in my vehicle, and I’m genuinely impressed. For just $80 for 25 square feet, this product delivers performance that rivals materials costing twice as much — and with far less hassle. If you're on the fence......Just buy it! You will not be disappointed.
Easy to Install: Unlike traditional sound deadening products that are stiff, sharp, and temperature-sensitive, this mat is soft, flexible, and easy to work with. I cut it cleanly with regular scissors and pressed it into tight spaces using just my fingers, so if in you don't have a roller or install tool, a good pair of scissors and your hands can get the job done. With other brands like Dynamat, the aluminum layer often leaves micro cuts on your hands and tears up your fingertips, but Siless does not due the acoustic layer being on top and above the aluminum layer that holds the butyl layer. So, it's very easy on your hands.
Even in cooler temperatures (around 50°F), I had no trouble applying it but it goes on better heated. If warm outside, I would leave the entire box out in the sun for at least 30 minutes when it's warm or heats it's very pliable and easy to mold. Make sure its where you want it because once applied it's not ever falling off. and it became even more pliable and easy to mold. No heat gun, no mess — just straightforward application.
I installed 40–50 square feet throughout the interior, covering everything except the headliner and the flooring forward of the rear seat. The difference in cabin noise is astonishing. I can turn my radio up concert loud with gut-punching bass, and from outside the car, it sounds like a factory sound system at mid volume. I was blown away by how well it contains sound — both inside out and outside in.
My exhaust is pretty aggressive and now is barely audible from inside the cabin. While driving, it almost sounds like a stock factory setup. The Siless matting actually changed the driving experience and feels refined.
If you're skeptical about sound deadening gimmicks, I get it, but this is the first product I've used and when I needed more, I went Stright to the 3 in 1 Hybrid matting and purchased it again. I love researching before buying and that's very uncommon for me to do.
Note: Proper installation is key, and it does take time and patience. But if installed correctly and in the right places, it works better previously used from paint-on sound deadening to Dynamat.
Update Nov, 2025
After using it this in 4 separate vehicles now. I feel the Siless’s 3 in 1 Hybrid has nailed it for best budget deadener that is better than dynamat extreme in performance and installation
Protip: buy a roll of 2-3” aluminum tape and tape the seams. After trimming the edges tend to very sticky between the panels. I ran a strip of aluminum tape over the seems to create a better seal and true moisture
I used it on four vehicles now and have I have not been paid to review and purchased every order myself.
3 in 1 Hybrid deadener by Siless is the best all around easy to apply sound deadner period!
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Reviewed in the United States on September 29, 2025
★★★★★ 5
Top quality
Model: SLH20025
This Siless Hybrid 3-in-1 sound deadening mat is easy to work with and feels high-quality. The butyl material is thick and pliable, making it simple to cut and fit into doors, floors, or panels.
After installation, road noise and vibrations are noticeably reduced, and it also seems to improve the overall cabin feel. No bad smell.
At 25 sq ft per roll, it’s a good value for anyone looking to dampen noise and improve car acoustics. Overall, a solid, effective option for automotive soundproofing. Used on a Fiesta ST.
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Reviewed in the United States on February 15, 2026
★★★★★ 5
Made a big improvement in cabin noise—highly recommend
Model: SLH20025
Siless Hybrid made a huge difference in reducing noise in the floor of my truck cabin. In some areas, there was basically just bare sheet metal between the inside and outside, so adding this really helped the truck feel more solid and noticeably quieter on the road.
I used Kilmat on the doors, and honestly I wish I had used Siless Hybrid there too, but it was too late by the time I realized the difference. This material is very sticky, easy to cut, and simple to apply, which made the install pretty smooth.
Just a heads-up: the tacky side gets messy and will bond to clothing really easily, so be careful during installation. Overall, I’d definitely buy it again—great product with real results.
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Reviewed in the United States on December 2, 2025