Okay, so as an avid autocrosser, I'm obviously going to look at modifying my car to help me perform better. I'm looking to do two easy things to keep my competitive in D-Stock, my new class of choice (locally). I'm looking at tires, but also know that exhaust can make a lot of difference in a turbocharged car.

D-Stock requires all downstream cats, but what about resonators? I don't want to do any more cutting than I have to; in fact, a true bolt-on system would be preferable. Anybody have any good suggestions? I'm still in my researching phase right now, so any input is good input.

 

Take a look at the Akrapovic exhaust it is complete bolt on, you can get the turbo back or just the down pipe.

 

A catback by itself doesn't do very much at all, except lighten your wallet.

 

Craig Wilcox who is former Nat'l champ in a MINI would tell you Quiksilver is the best. He is using it on his 2008 D-stock Cooper S.

 

The right one will also lighten your car.

Ah, very nice. That's endorsement enough for me. I'm curious to know where his stock exhaust ends and the Quicksilver begins, though, in regards to cats and resonators and the like. The weight reduction, going down to 18lbs in the exhaust, in addition to the claimed gains (I'd be happy with 10hp, let alone the 30 they claim) will really make a difference in a competitive DS class.

 

Can you have a tune in D-stock? If so, that's what I have found to make a huge improvement over stock for performance. HUGE!

 

According to section 13.9 of the SCCA Solo rulebook:

So I'm going to read that as no tunes are allowed. I'm also locked into 16x6.5 inch wheels, which are going to be tough to find in general if they're not OE, tougher still looking for lighter weight that what I'm running. I've been looking at Mazda wheels, actually, as well as perhaps just picking up a set of the lightweight 16" wheels from MINI. That drop in weight would be nice as it would offset the added weight of the wheels, as well as reducing all-important rotational weight. Unsprung weight is a real killer, so where you can drop a few pounds, you really make out better in the end.

I know the exhaust question seems like a very noob-like question, but I come from a class-winning Subaru Impreza previously, so I do know about the rules of autocrossing. I, however, do not know about the various parts offered for the MINI and their benefits and downfalls, so that is why I asked the question. Adding an exhaust downwind of the cat will increase spool, drop weight and perhaps even add a couple horsepower, all of which are major benefits in what will be a very competitive D-Stock class.

 

Try 949 Racing for wheels. Jan has them on his GP. Very light and Very cheap!

 

I just checked; it looks like they only have 15" and 17" wheels. When you're running stock class, you're limited to the exact size wheels that came on your car; in my case, that's 16x6.5. I can go as wide as I want when it comes to tires, but they have to fit a 16x6.5 inch wheel... I think that's gonna be where my issue lies. But I'll certainly keep my eyes out. Rota makes 6.5 inch wide wheels, but I've heard things about their build quality, and how it also makes it so they aren't always the lightest wheels on the market. Honestly, if I can get some Miata or MINI wheels, they'd probably be cheaper too because they're lightly used and OEM never goes for as much as aftermarket.

 

Bringing thread back to life. What is the dia of the QS system? 2.25 or 2.5"? For that matter what is the stock systems dia? 2"?

 

You can use any size wheel that was available from the factory on your model car.

 

Wouldn't you be able to use 17" as Cooper S had 17" standard on the chili pack and optional on non chili models. My non chili MCS was ordered with 17" flame spoke wheels.

 

In D stock you can run either 17x7, or 16x6.5 since those are both the original equipment sizes. It doesn't matter what packages came on the car either size is legal.

 

No mufflers or resonators are required for a stock class exhaust in SCCA Solo2. Mine has the factory catback replaced with just a 3" (or maybe it's 2.5"??) straight pipe from the cat to the rear bumper. It sounds glorious and is not particularly loud or offensive sounding. I forget the exact weight savings, but I want to say at least 20 lbs.