Reinforced ARP cylinder head studs AUDI 2.5 TFSI DAZA DNWA

The engines concerned

Audi's 2.5 TFSI turbocharged in-line five-cylinder (2,480 cc, 82.5 mm bore, 92.8 mm stroke), codes DAZA and DNWA, powers the Audi RS3 8V (400 hp, 2017-2020), the Audi TT RS FV (400 hp, from 2016) and the KTM X-Bow GT-XR (500 hp, from 2022).

Originally, the head of the DAZA, like that of the DNWA, is held by M10 x 1.5 cylinder head bolts, 10 mm in diameter and 120 mm long (part WHT007848D). ARP replaces them with a stud kit of your choice, in ARP2000 or in Custom Age 625+.

Reinforced ARP cylinder head studs

Every combustion cycle pushes the cylinder head upwards. The head fasteners resist it by keeping a constant clamping pressure on the gasket; if that pressure drops, the seal is no longer guaranteed.

Two ARP part numbers are offered: the 204-4708 in ARP2000, in the « undercut » version according to the 2026 ARP list, and the 404-4708 in Custom Age 625+. Their instruction sheets follow the same fitting order: gasket and head first, then studs screwed into the block by hand, washers fitted stamped side towards the head, and 12-point nuts tightened after ARP Ultra-Torque has been applied to the threads and under the nuts. For these kits, no specific strength value is published. As an estimate only, equivalent M10 fasteners are around 700 hp on a five-cylinder in ARP2000, and around 800 hp in Custom Age 625+.

Technical specifications

Tightening torque

For both kits: each stud is screwed into the block by hand, without torque. This kit's instruction sheet does not mention thread locker; ARP states that some engine builders use a medium-strength (blue) one on the block end, but never on the nuts, never with ARP grease, and only if tightening is finished before it hardens.

Both sheets ask for the washer seats on the head to be cleaned with brake cleaner and, if needed, for the block threads to be run through with a thread chaser.

Follow the tightening sequence recommended by the manufacturer and bring to torque in three stages; the stated values assume ARP lubricant on the threads and under the nuts.

No trace of oil under the washers: they are fitted dry, wiped on both sides, and the head seats are degreased for even tightening.

These values are taken from ARP instruction sheets 204-4708 and 404-4708; the official sheet in force prevails for the whole procedure, including the manufacturer's tightening sequence. Read the ARP 204-4708 instruction sheet; Read the ARP 404-4708 instruction sheet

Technical guide

To obtain the intended preload, ARP assembly grease must be present on the threads and under the nuts: the torque figures in the table are established with it.

The available grades

ARP undercut studs

On an undercut stud, ARP reduces the shank between the two threads. The studs then stretch more evenly from one to the next: the clamping force becomes more consistent and compensates for head gasket compression at installation, which reduces the risk of a blown gasket.

The ARP brand

ARP (Automotive Racing Products) was born in the early 1970s from the initiative of Gary Holzapfel, an engineer from the aerospace industry, determined to eliminate engine failures caused by weak fasteners in motorsport. The company designs and manufactures thousands of parts in California, in several material grades suited to each use.

Advantages over the original bolts

Criterion	Original head bolts	Reinforced ARP studs
Block threads	Stressed at every tightening	Preserved (studs fitted hand tight)

When studs become necessary

Standard fasteners remain suitable as long as the engine keeps its original combustion pressure. They reach their limits in the following cases:

• DAZA and DNWA with raised turbo boost or a larger turbo
• Compression ratio raised for more power
• Reinforced MLS head gasket, which requires a high and even preload
• Cylinder head that has already lifted or gasket that has already leaked
• Racing or track use, with repeated heat-ups and frequent teardowns

Vehicle compatibility

OEM reference: WHT007848D

Why is it the most cost-effective solution?

When a 2.5 TFSI goes beyond its standard power output, the sealing of the head gasket depends first on the clamping load of the original bolts. ARP studs, screwed into the block by hand, offer a higher load, at a cost that is out of proportion with a cylinder head to redo, gasket and labour included.

Consider a reinforced head gasket

Reinforced fasteners are only fully worthwhile with a head gasket able to resist the same pressure. We offer the following part for this engine: