Building a stainless cat-back for a daily-driven ute
Quiet at the lights, mean at full noise, and no drone on the highway run to Wollongong. Here's the full bend-by-bend on the 409 stainless system we built last week.
Blog system
Eleven token-driven editorial primitives for the Oak Flats Mufflermen public site — a filterable index grid, cards, a featured hero, the full post layout with rich body slots, author byline, category filters, related row, newsletter CTA, prev/next nav, and a scroll-spy table of contents. Every value is drawn from the central design tokens, so light, dark, and responsive all re-theme from one place.
Production answer
Blog system is a reusable Oak Flats Muffler Men UI primitive with documented states, accessibility expectations, theme behavior, and implementation evidence.
Primary CTAReview Blog system states
Generative search brief
Blog system: Eleven token-driven editorial primitives for the Oak Flats Mufflermen public site — a filterable index grid, cards, a featured hero, the full post layout with rich body slots, author byline, category filters, related row, newsletter CTA, prev/next nav, and a scroll-spy table of contents. Every value is drawn from the central design tokens, so light, dark, and responsive all re-theme from one place.
Blog shared DNA
Connected editorial primitives
The blog system now advertises its shared contract at the index level: section patterns provide layout, typography sets reading hierarchy, surfaces frame editorial cards, and action DNA handles conversion and sharing.
- Editorial surfaces
- Cards, heroes, article shells, TOCs, and related rows share one section taxonomy.
- Reading rhythm
- Typography tokens control headline scale, lede density, body cadence, and captions.
- Conversion handoff
- Newsletter and share actions inherit Button DNA, focus rings, and feedback states.
Featured post hero
Large editorial hero for the lead story — image, category chip, headline, dek, expanded byline, and a metallic-paint CTA. Reverses to a stacked layout under 880px.
Mandrel vs crush bends: where your flow actually goes
A crush bend looks fine from the outside and chokes the gas the moment it turns. We cut three identical 2.5-inch sections and put them on the flow bench to settle the workshop argument once and for all.
Blog card
The atomic unit — cover image with category chip, clamped title and excerpt, and an author byline footer. Vertical for grids, horizontal for list rows. Hover lifts the card and gently scales the cover.
Blog index grid
A responsive, filterable card grid. The category filter is a keyboard-operable radio group; selecting a section narrows the grid live. Auto-fills from three columns down to one.
From the workshop
Latest from the bench
Mandrel vs crush bends: where your flow actually goes
A crush bend looks fine from the outside and chokes the gas the moment it turns. We cut three identical 2.5-inch sections and put them on the flow bench to settle the workshop argument once and for all.
Building a stainless cat-back for a daily-driven ute
Quiet at the lights, mean at full noise, and no drone on the highway run to Wollongong. Here's the full bend-by-bend on the 409 stainless system we built last week.
Killing cabin drone without killing the note
That 2,200 rpm drone on the freeway is a standing wave, not a personality flaw. Helmholtz resonators, a quarter-wave tube, and where we actually put them.
Rust rescue: when to patch and when to replace
Salt air off the lake eats mild-steel systems from the inside. A field guide to the tap test, the honest quote, and why we'll talk you out of a patch that won't last the warranty.
What changed when we re-laid out the weld cell
New TIG bench, a back-purge manifold, and a fixture table that finally squares the work. A look at how the bay changed and what it does for turnaround.
Headers, extractors, and the myth of the free pony
Equal-length, tri-Y, four-into-one — the geometry that actually moves the dyno line, and the marketing that doesn't. With real numbers from our own cell.
Author byline
Avatar (image or initials monogram), name, dateline, and reading time. Compact for cards; expanded adds the role and bio for post headers.
Table of contents
Scroll-spy navigation that highlights the section in view via IntersectionObserver. Anchors are keyboard focusable with a visible ring; the active marker extends and turns brand-red.
Share row
Round share controls with hover tooltips. The copy-link action writes the canonical URL to the clipboard and announces the result to assistive tech.
Prev / next nav
Two-up post navigation with direction arrows, category, and a clamped title. Falls back to muted end-of-log placeholders when there is no neighbour, and stacks under 640px.
Related posts row
A three-up row of related cards under an article. Collapses to two, then one column on narrow viewports.
Blog newsletter CTA
Conversion block built on the central button DNA — metallic-red primary that shifts to metallic-amber on hover. Carbon-fibre weave under the surface, single email field, and status feedback.
Responsive composition
The index grid at three breakpoints — 320 mobile, 768 tablet, and full desktop — proving the grid, filter bar, and cards reflow cleanly across the range.
Full post layout — sample article
The complete reading experience: header chip + dateline, hero, lede, rich body slots (headings, paragraphs, list, inline media, pull-quote), a sticky table-of-contents aside, then tags and a share row in the footer.
Exhaust tech8 min read
Mandrel vs crush bends: where your flow actually goes
Every workshop has the same argument on a quiet Friday: does a crush bend really cost you anything if the diameter's right? We stopped arguing and put it on the flow bench.
The bench argument
A crush bend pinches the inside radius of the tube as it turns. The nominal diameter is still 2.5 inches on the straights, but at the apex of the bend the cross-section collapses to an oval — and gas does not like turning a sharp corner through a smaller hole. A mandrel bend keeps a round, full-bore section all the way through the curve because a steel ball is drawn through the tube while it forms.
- Crush bend: cheap, fast, fine on a low-flow mild-steel muffler.
- Mandrel bend: holds full bore, costs more, earns it under load.
- Where it matters most: the first three bends off the collector.
The pipe diameter on the box is a promise the crush bend quietly breaks at every corner.
How we tested it
We cut three 2.5-inch sections to the same length, each with a single 90-degree bend: one crush, one press-formed, one mandrel. Same flow bench, same depression, same operator. We logged CFM at a fixed pressure drop and ran each section three times to average out the noise.
What the numbers said
The mandrel section flowed roughly 14 percent more than the crush bend at the same pressure drop. The press-formed section landed in the middle, closer to the mandrel than most of the crew guessed. On a single bend that gap sounds small — but a typical cat-back has six to nine direction changes, and the losses stack.
The verdict
For a quiet daily that never sees the top of the tacho, a well-made press-formed system is honest value. For anything that breathes hard — a tuned engine, a tow rig under load, a build going on the dyno — mandrel pays for itself in the first three bends. We'll always tell you which one your car actually needs.
Editorial index composition
Featured hero, filterable index grid, related row, and the newsletter CTA composed into one long-scroll blog landing surface.
Mandrel vs crush bends: where your flow actually goes
A crush bend looks fine from the outside and chokes the gas the moment it turns. We cut three identical 2.5-inch sections and put them on the flow bench to settle the workshop argument once and for all.
Every entry
The full log
Mandrel vs crush bends: where your flow actually goes
A crush bend looks fine from the outside and chokes the gas the moment it turns. We cut three identical 2.5-inch sections and put them on the flow bench to settle the workshop argument once and for all.
Building a stainless cat-back for a daily-driven ute
Quiet at the lights, mean at full noise, and no drone on the highway run to Wollongong. Here's the full bend-by-bend on the 409 stainless system we built last week.
Killing cabin drone without killing the note
That 2,200 rpm drone on the freeway is a standing wave, not a personality flaw. Helmholtz resonators, a quarter-wave tube, and where we actually put them.
Rust rescue: when to patch and when to replace
Salt air off the lake eats mild-steel systems from the inside. A field guide to the tap test, the honest quote, and why we'll talk you out of a patch that won't last the warranty.
What changed when we re-laid out the weld cell
New TIG bench, a back-purge manifold, and a fixture table that finally squares the work. A look at how the bay changed and what it does for turnaround.
Headers, extractors, and the myth of the free pony
Equal-length, tri-Y, four-into-one — the geometry that actually moves the dyno line, and the marketing that doesn't. With real numbers from our own cell.