4 Cyl. Chip #4: High-Performance code 310HP
Reviewed by Mark Wiens (USA)
Well, after installing a Sport 300 tranny and a new PUK +35% torque clutch, and with the sun shining, I replaced my #3 Hi-Torque chip with the #4 310BHP chip for review.

Burning it in with a nice long idle with AC Off and then On, I took it for a spin. It's been a long time since I ran with the original stock SE chip, but I certainly recall what a difference the S4s MkV chip made when I first installed it. I was also pleased when I switched to the Hi-Torque chip, for a nice additional bit of torque surge for passing cars on a two lane road without hesitation. I've been running with the Hi-Torque chip now for just over a year and have been quite happy with it.

At one point, partially due to changes in the weather, I had to reset the chip and have it re-learn winter time, hehe. I found by adjusting the wastegate a bit higher, from 0.58 (where it was originally) to 0.68 based on Marcus' recommendation that it should not be below 0.65 and should range from 0.65-0.75, this was a 'big' help in eliminating the 3K flatspot.

For reference, I've got a dual Magnaflow muffler system (hi flow straight-thru with glass packed walls), a K&N air filter and a TAS Blow-off Valve from Sanj, which may affect things a bit, but everything else is stock.

According to Marcus at PUK, the Hi-Torque chip is 285HP (same as the S4s chip), but with the additional torque. Initially, I wanted to be careful and not overtax the engine and tranny by going to a higher power chip. But, as it happened, my pinion shaft bearing was weak anyway, with 50k miles on the car, and so was my clutch. And after running with the Hi-Torque and doing a lot of WOT (wide-open-throttle) tests using Freescan... over a period of 12 months, the tranny was getting noisier and finally, the clutch began to slip, just before I received the 310BHP chip. So I waited to get that fixed and run for a while before installing it. Here are my observations;

1. The 310BHP definitely seems to bring up boost higher for the same amount of gas pedal travel than the Hi-Torque chip.

2. The 310BHP chip definitely climbs a bit faster (acceleration) in the upper rpm regions, whereas the Hi-Torque chip tends to level off up there at maybe 4500 to Redline (horsepower levels off). In other words,
the 310BHP continues to accelerate (increased horsepower). This is, of course, due to the 25 additional horsepower.

3. On the Hi-Torque chip I periodically noticed some gas fumes when doing a pedal-to-the-floor WOT throttling thru the gears at 2800 rpm on up, whereas I haven't noticed any on the 310BHP chip on a run in the same location (freeway onramp) full boost. I'm guessing this is because of a higher fuel dump percentage into the intake at lower rpms during WOT with the Hi-Torque chip... but it could be due to other things too. I did replace the one-way check valve last year, which helped immensely. But, I notice on the 310BHP chip, though the boost comes in earlier, it doesn't peak out the boost gauge as high as the Hi-Torque chip initially did. This could be partially due to the ECM learning process, but I've reset several times during the course of the last year.

4. The one thing I notice more than anything, is that one thing I liked about the Hi-Torque chip, is that things are very controllable up to approximately 50-60% throttle. The boost only goes up to .65 or so
there, but then when giving her more pedal or WOT during a quick pass, it lunges forward and I'm able to have great confidence in passing under tight conditions. The 310BHP also tends to hit around the .65-.70 bar boost but it seems like it does it at a much earlier throttle, like 30-40%, then climbs much higher at 50-70%. On the Hi-Torque chip, the throttle vs boost acts a tad more like a switch within a window, versus the 310BHP which is a bit more linear throughout the boost range vs. throttle position/load. I was worried at first that this might render the 310BHP chip a bit less controllable in the lower rpm's above 3k, but I was wrong, it is very controllable due to it's apparent, more linear response range.

5. The 310BHP chip does definitely have a nice noticeable increase in acceleration at mid to higher rpm's. Part of the reason the Hi-Torque acceleration at higher rpm's levels off more noticeably than the earlier S4s chip, is because, due to the higher torque at lower revs, you have essentially already reached a higher speed 'earlier', so you essentially get put back in the seat earlier as opposed to later at higher revs with the S4s chip. But, the 310BHP chip seems to be a very nice balance of both worlds, due to its higher power.

So, at this point, I've decided I definitely like the 310BHP chip upgrade and though I was concerned about losing some lower rpm torque that I had with the Hi-Torque chip, I think, due to the higher power
curve and the smoother, more linear boost, it definitely makes up for it very very well! So I don't find the issue I thought I might have, requiring a downshift to get to the right rpm's to make a tedious two-lane car pass. The power is there! It's smooth and linear... and goes like a bat outa hell when progressively reaching wide open throttle in 4th. I don't think I'll be going back to the Hi-Torque chip. :)

Just as a final note. I hear that many people have had no issues with stock clutches with these higher power chips. But, the S4s was given a stronger clutch from the factory (due to some clutch failures on the
early ones), than the older SE's. So, either be observant and careful not to pack too much off-the-line torque and power onto a stock SE clutch, or consider a higher torque (+35%) PUK clutch or an S4s clutch (which requires an additional flywheel purchase). According to PUK, the +35% clutch is stronger than the S4s clutch. Also, the S4s actually requires less clutch pedal pressure than the PUK, which my mechanic confirmed by its design.

Best Regards,

Mark (91SE 310BHP) Wiens